diff --git a/build.gradle b/build.gradle
index 702ed44..b098a33 100644
--- a/build.gradle
+++ b/build.gradle
@@ -8,7 +8,7 @@ plugins {
 }
 
 wrapper {
-    gradleVersion = "${rootProject.property('gradle.wrapper.version')}"
+    gradleVersion = libs.versions.gradle.get()
     distributionType = Wrapper.DistributionType.ALL
 }
 
diff --git a/config/src/main/java/org/xbib/config/ConfigParams.java b/config/src/main/java/org/xbib/config/ConfigParams.java
index 17a1944..2caa363 100644
--- a/config/src/main/java/org/xbib/config/ConfigParams.java
+++ b/config/src/main/java/org/xbib/config/ConfigParams.java
@@ -179,12 +179,12 @@ public class ConfigParams implements Comparable<ConfigParams> {
                 fileLocations;
     }
 
-    public static class SuffixedReader {
+    static class SuffixedReader {
         Reader reader;
         String suffix;
     }
 
-    public static class JdbcLookup {
+    static class JdbcLookup {
         Connection connection;
         String statement;
         String[] params;
diff --git a/config/src/main/java/org/xbib/config/NullConfigLogger.java b/config/src/main/java/org/xbib/config/NullConfigLogger.java
index e6279dc..fb5458c 100644
--- a/config/src/main/java/org/xbib/config/NullConfigLogger.java
+++ b/config/src/main/java/org/xbib/config/NullConfigLogger.java
@@ -2,6 +2,9 @@ package org.xbib.config;
 
 public class NullConfigLogger implements ConfigLogger {
 
+    public NullConfigLogger() {
+    }
+
     @Override
     public void info(String string) {
     }
diff --git a/config/src/main/java/org/xbib/config/SystemConfigLogger.java b/config/src/main/java/org/xbib/config/SystemConfigLogger.java
index fd6db17..b85ec46 100644
--- a/config/src/main/java/org/xbib/config/SystemConfigLogger.java
+++ b/config/src/main/java/org/xbib/config/SystemConfigLogger.java
@@ -2,6 +2,9 @@ package org.xbib.config;
 
 public class SystemConfigLogger implements ConfigLogger {
 
+    public SystemConfigLogger() {
+    }
+
     @Override
     public void info(String string) {
         System.err.println("info: " + string);
diff --git a/content-core/build.gradle b/content-core/build.gradle
index ca4258e..a5b0688 100644
--- a/content-core/build.gradle
+++ b/content-core/build.gradle
@@ -1,4 +1,4 @@
 dependencies {
     api project(':content-api')
-    api "com.fasterxml.jackson.core:jackson-core:${project.property('jackson.version')}"
+    api libs.jackson.core
 }
diff --git a/content-core/src/main/java/org/xbib/content/core/AbstractXContentGenerator.java b/content-core/src/main/java/org/xbib/content/core/AbstractXContentGenerator.java
index 22ec355..a4933b2 100644
--- a/content-core/src/main/java/org/xbib/content/core/AbstractXContentGenerator.java
+++ b/content-core/src/main/java/org/xbib/content/core/AbstractXContentGenerator.java
@@ -12,6 +12,9 @@ public abstract class AbstractXContentGenerator implements XContentGenerator {
 
     protected XContentGenerator generator;
 
+    public AbstractXContentGenerator() {
+    }
+
     public AbstractXContentGenerator setGenerator(XContentGenerator generator) {
         this.generator = generator;
         return this;
diff --git a/content-core/src/main/java/org/xbib/content/core/AbstractXContentParser.java b/content-core/src/main/java/org/xbib/content/core/AbstractXContentParser.java
index 1efe8ca..adc0668 100644
--- a/content-core/src/main/java/org/xbib/content/core/AbstractXContentParser.java
+++ b/content-core/src/main/java/org/xbib/content/core/AbstractXContentParser.java
@@ -6,19 +6,15 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 
-/**
- *
- */
 public abstract class AbstractXContentParser implements XContentParser {
 
-    //private static final MapFactory SIMPLE_MAP_FACTORY = HashMap::new;
-
-    //private static final MapFactory TINY_MAP_FACTORY = TinyMap::builder;
-
     private boolean losslessDecimals;
 
     private boolean base16Checks;
 
+    public AbstractXContentParser() {
+    }
+
     protected abstract MapFactory getMapFactory();
 
     protected abstract MapFactory getOrderedMapFactory();
diff --git a/content-core/src/main/java/org/xbib/content/core/XContentService.java b/content-core/src/main/java/org/xbib/content/core/XContentService.java
index 69bb2f8..141079b 100644
--- a/content-core/src/main/java/org/xbib/content/core/XContentService.java
+++ b/content-core/src/main/java/org/xbib/content/core/XContentService.java
@@ -22,6 +22,9 @@ public class XContentService {
         }
     }
 
+    private XContentService() {
+    }
+
     public static XContentBuilder builder(String name) throws IOException {
         return xcontents.containsKey(name) ? DefaultXContentBuilder.builder(xcontents.get(name)) : null;
     }
diff --git a/content-json/build.gradle b/content-json/build.gradle
index 1f48e0d..a855a9b 100644
--- a/content-json/build.gradle
+++ b/content-json/build.gradle
@@ -1,7 +1,5 @@
 dependencies {
     api project(':content-core')
-    api "com.fasterxml.jackson.core:jackson-databind:${project.property('jackson.version')}"
-    testImplementation("org.mockito:mockito-core:${project.property('mockito.version')}") {
-        exclude group: 'org.hamcrest'
-    }
+    api libs.jackson.databind
+    testImplementation libs.mockito.inline
 }
diff --git a/content-json/src/main/java/module-info.java b/content-json/src/main/java/module-info.java
index faff327..8b438e2 100644
--- a/content-json/src/main/java/module-info.java
+++ b/content-json/src/main/java/module-info.java
@@ -7,7 +7,7 @@ module org.xbib.content.json {
     exports org.xbib.content.json.mergepatch;
     exports org.xbib.content.json.patch;
     exports org.xbib.content.json.pointer;
-    requires org.xbib.content.core;
-    requires com.fasterxml.jackson.databind;
+    requires transitive org.xbib.content.core;
+    requires transitive com.fasterxml.jackson.databind;
     provides XContent with org.xbib.content.json.JsonXContent;
 }
diff --git a/content-json/src/main/java/org/xbib/content/json/JsonXContent.java b/content-json/src/main/java/org/xbib/content/json/JsonXContent.java
index ebbb797..3f098c8 100644
--- a/content-json/src/main/java/org/xbib/content/json/JsonXContent.java
+++ b/content-json/src/main/java/org/xbib/content/json/JsonXContent.java
@@ -23,6 +23,7 @@ import java.nio.charset.StandardCharsets;
 public class JsonXContent implements XContent {
 
     private static final JsonXContent jsonXContent;
+
     private static final JsonFactory jsonFactory;
 
     static {
diff --git a/content-json/src/main/java/org/xbib/content/json/jackson/JsonNodeReader.java b/content-json/src/main/java/org/xbib/content/json/jackson/JsonNodeReader.java
index 8b74577..ccbba12 100644
--- a/content-json/src/main/java/org/xbib/content/json/jackson/JsonNodeReader.java
+++ b/content-json/src/main/java/org/xbib/content/json/jackson/JsonNodeReader.java
@@ -3,6 +3,7 @@ package org.xbib.content.json.jackson;
 import com.fasterxml.jackson.core.JsonLocation;
 import com.fasterxml.jackson.core.JsonParseException;
 import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.io.ContentReference;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.MappingIterator;
 import com.fasterxml.jackson.databind.ObjectMapper;
@@ -69,20 +70,8 @@ public final class JsonNodeReader {
      *                             from the stream
      */
     public JsonNode fromInputStream(final InputStream in) throws IOException {
-        JsonParser parser = null;
-        MappingIterator<JsonNode> iterator = null;
-
-        try {
-            parser = reader.getFactory().createParser(in);
-            iterator = reader.readValues(parser);
+        try (JsonParser parser = reader.getFactory().createParser(in); MappingIterator<JsonNode> iterator = reader.readValues(parser)) {
             return readNode(iterator);
-        } finally {
-            if (parser != null) {
-                parser.close();
-            }
-            if (iterator != null) {
-                iterator.close();
-            }
         }
     }
 
@@ -94,35 +83,21 @@ public final class JsonNodeReader {
      * @throws java.io.IOException malformed input, or problem encountered when reading
      *                             from the reader
      */
-    public JsonNode fromReader(final Reader r)
-            throws IOException {
-        JsonParser parser = null;
-        MappingIterator<JsonNode> iterator = null;
-
-        try {
-            parser = reader.getFactory().createParser(r);
-            iterator = reader.readValues(parser);
+    public JsonNode fromReader(final Reader r) throws IOException {
+        try (JsonParser parser = reader.getFactory().createParser(r); MappingIterator<JsonNode> iterator = reader.readValues(parser)) {
             return readNode(iterator);
-        } finally {
-            if (parser != null) {
-                parser.close();
-            }
-            if (iterator != null) {
-                iterator.close();
-            }
         }
     }
 
-    /**
-     *
-     */
     private static final class JsonParseExceptionBuilder {
-        private JsonParser jsonParser;
+
+        private final JsonParser jsonParser;
+
         private JsonLocation location;
 
         private JsonParseExceptionBuilder(final JsonParser jsonParser, final Object source) {
             this.jsonParser = jsonParser;
-            location = new JsonLocation(source, 0L, 1, 1);
+            location = new JsonLocation(ContentReference.construct(false, source), 0L, 1, 1);
         }
 
         private JsonParseExceptionBuilder setLocation(final JsonLocation location) {
diff --git a/content-json/src/main/java/org/xbib/content/json/mergepatch/JsonMergePatchDeserializer.java b/content-json/src/main/java/org/xbib/content/json/mergepatch/JsonMergePatchDeserializer.java
index 12cd019..2be44ea 100644
--- a/content-json/src/main/java/org/xbib/content/json/mergepatch/JsonMergePatchDeserializer.java
+++ b/content-json/src/main/java/org/xbib/content/json/mergepatch/JsonMergePatchDeserializer.java
@@ -17,6 +17,9 @@ import java.io.IOException;
  * write our own here.
  */
 public final class JsonMergePatchDeserializer extends JsonDeserializer<JsonMergePatch> {
+
+    public JsonMergePatchDeserializer() {}
+
     @Override
     public JsonMergePatch deserialize(final JsonParser jp, final DeserializationContext ctxt)
             throws IOException {
diff --git a/content-json/src/test/java/org/xbib/content/json/jackson/JsonNodeReaderTest.java b/content-json/src/test/java/org/xbib/content/json/jackson/JsonNodeReaderTest.java
index 6a0a4c7..75aa96e 100644
--- a/content-json/src/test/java/org/xbib/content/json/jackson/JsonNodeReaderTest.java
+++ b/content-json/src/test/java/org/xbib/content/json/jackson/JsonNodeReaderTest.java
@@ -15,27 +15,24 @@ import java.io.Reader;
 import java.io.StringReader;
 import java.nio.charset.StandardCharsets;
 
-/**
- *
- */
 public final class JsonNodeReaderTest {
 
     @Test
-    public void streamIsClosedOnRead()
-            throws IOException {
-        final InputStream in = spy(new ByteArrayInputStream("[]".getBytes(StandardCharsets.UTF_8)));
+    public void streamIsClosedOnRead() throws IOException {
+        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream("[]".getBytes(StandardCharsets.UTF_8));
+        final InputStream in = spy(byteArrayInputStream);
         final JsonNode node = new JsonNodeReader().fromInputStream(in);
         verify(in).close();
-        assertEquals(node, new ObjectMapper().readTree(new ByteArrayInputStream("[]".getBytes("UTF-8"))));
+        assertEquals(node, new ObjectMapper().readTree(new ByteArrayInputStream("[]".getBytes(StandardCharsets.UTF_8))));
     }
 
     @Test
-    public void readerIsClosedOnRead()
-            throws IOException {
-        final Reader reader = spy(new StringReader("[]"));
+    public void readerIsClosedOnRead() throws IOException {
+        StringReader stringReader = new StringReader("[]");
+        final Reader reader = spy(stringReader);
         final JsonNode node = new JsonNodeReader().fromReader(reader);
-        assertEquals(node, new ObjectMapper().readTree(new StringReader("[]")));
         verify(reader).close();
+        assertEquals(node, new ObjectMapper().readTree(new StringReader("[]")));
     }
 
     @Test
diff --git a/content-rdf/src/main/java/module-info.java b/content-rdf/src/main/java/module-info.java
index 49d4efc..65ea72c 100644
--- a/content-rdf/src/main/java/module-info.java
+++ b/content-rdf/src/main/java/module-info.java
@@ -10,7 +10,7 @@ module org.xbib.content.rdf {
     exports org.xbib.content.rdf.io.turtle;
     exports org.xbib.content.rdf.io.xml;
     exports org.xbib.content.rdf.util;
-    requires org.xbib.content.resource;
-    requires org.xbib.content.xml;
-    requires org.xbib.content.json;
+    requires transitive org.xbib.content.resource;
+    requires transitive org.xbib.content.xml;
+    requires transitive org.xbib.content.json;
 }
diff --git a/content-rdf/src/main/java/org/xbib/content/rdf/internal/DefaultRdfGraph.java b/content-rdf/src/main/java/org/xbib/content/rdf/internal/DefaultRdfGraph.java
index a4e64fd..5448b88 100644
--- a/content-rdf/src/main/java/org/xbib/content/rdf/internal/DefaultRdfGraph.java
+++ b/content-rdf/src/main/java/org/xbib/content/rdf/internal/DefaultRdfGraph.java
@@ -23,6 +23,9 @@ public class DefaultRdfGraph implements RdfGraph<RdfGraphParams> {
 
     private final Map<IRI, Resource> resources = new LinkedHashMap<>();
 
+    public DefaultRdfGraph() {
+    }
+
     @Override
     public Iterator<Resource> getResources() {
         return resources.values().stream().iterator();
diff --git a/content-rdf/src/main/java/org/xbib/content/rdf/io/source/BaseStreamProcessor.java b/content-rdf/src/main/java/org/xbib/content/rdf/io/source/BaseStreamProcessor.java
index b0f2609..009909b 100644
--- a/content-rdf/src/main/java/org/xbib/content/rdf/io/source/BaseStreamProcessor.java
+++ b/content-rdf/src/main/java/org/xbib/content/rdf/io/source/BaseStreamProcessor.java
@@ -10,6 +10,9 @@ import java.net.URLConnection;
  */
 public abstract class BaseStreamProcessor {
 
+    public BaseStreamProcessor() {
+    }
+
     protected abstract void startStream() throws IOException;
 
     protected abstract void endStream() throws IOException;
diff --git a/content-rdf/src/main/java/org/xbib/content/rdf/util/TreeMultiMap.java b/content-rdf/src/main/java/org/xbib/content/rdf/util/TreeMultiMap.java
deleted file mode 100644
index 545dedc..0000000
--- a/content-rdf/src/main/java/org/xbib/content/rdf/util/TreeMultiMap.java
+++ /dev/null
@@ -1,97 +0,0 @@
-package org.xbib.content.rdf.util;
-
-import java.util.Collection;
-import java.util.LinkedHashSet;
-import java.util.Map;
-import java.util.Set;
-import java.util.TreeMap;
-
-/**
- * A {@link TreeMap} based multi map. The keys ore ordered.
- * @param <K> te key type
- * @param <V> the value type
- */
-public class TreeMultiMap<K, V> implements MultiMap<K, V> {
-
-    private final Map<K, Set<V>> map = new TreeMap<>();
-
-    @Override
-    public int size() {
-        return map.size();
-    }
-
-    @Override
-    public void clear() {
-        map.clear();
-    }
-
-    @Override
-    public boolean isEmpty() {
-        return map.isEmpty();
-    }
-
-    @Override
-    public boolean containsKey(K key) {
-        return map.containsKey(key);
-    }
-
-    @Override
-    public Set<K> keySet() {
-        return map.keySet();
-    }
-
-    @Override
-    public boolean put(K key, V value) {
-        Set<V> set = map.get(key);
-        if (set == null) {
-            set = new LinkedHashSet<>();
-            set.add(value);
-            map.put(key, set);
-            return true;
-        } else {
-            set.add(value);
-            return false;
-        }
-    }
-
-    @Override
-    public void putAll(K key, Collection<V> values) {
-        Set<V> set = map.get(key);
-        if (set == null) {
-            set = new LinkedHashSet<>();
-            map.put(key, set);
-        }
-        set.addAll(values);
-    }
-
-    @Override
-    public Collection<V> get(K key) {
-        return map.get(key);
-    }
-
-    @Override
-    public Set<V> remove(K key) {
-        return map.remove(key);
-    }
-
-    @Override
-    public boolean remove(K key, V value) {
-        Set<V> set = map.get(key);
-        return set != null && set.remove(value);
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-        return obj != null && obj instanceof TreeMultiMap && map.equals(((TreeMultiMap) obj).map);
-    }
-
-    @Override
-    public int hashCode() {
-        return map.hashCode();
-    }
-
-    @Override
-    public String toString() {
-        return map.toString();
-    }
-}
diff --git a/content-rdf/src/test/java/org/xbib/content/rdf/util/MultiMapTest.java b/content-rdf/src/test/java/org/xbib/content/rdf/util/MultiMapTest.java
index fd04e66..ece8abf 100644
--- a/content-rdf/src/test/java/org/xbib/content/rdf/util/MultiMapTest.java
+++ b/content-rdf/src/test/java/org/xbib/content/rdf/util/MultiMapTest.java
@@ -5,9 +5,6 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 import org.junit.jupiter.api.Test;
 import java.util.Arrays;
 
-/**
- *
- */
 public class MultiMapTest {
 
     @Test
@@ -23,19 +20,4 @@ public class MultiMapTest {
         map.putAll("a", Arrays.asList("d", "e"));
         assertEquals("[b, c, d, e]", map.get("a").toString());
     }
-
-    @Test
-    public void testTreeMultiMap() {
-        TreeMultiMap<String, String> map = new TreeMultiMap<>();
-        map.put("a", "b");
-        map.put("b", "c");
-        map.put("a", "c");
-        assertTrue(map.containsKey("a"));
-        assertTrue(map.containsKey("b"));
-        assertEquals("[a, b]", map.keySet().toString());
-        assertEquals("[b, c]", map.get("a").toString());
-        assertEquals("[c]", map.get("b").toString());
-        map.putAll("a", Arrays.asList("d", "e"));
-        assertEquals("[b, c, d, e]", map.get("a").toString());
-    }
 }
diff --git a/content-resource/build.gradle b/content-resource/build.gradle
index a9255cd..857d9f7 100644
--- a/content-resource/build.gradle
+++ b/content-resource/build.gradle
@@ -1,4 +1,4 @@
 dependencies {
-    api "org.xbib:net-url:${project.property('xbib.net.version')}"
-    testImplementation "com.fasterxml.jackson.core:jackson-databind:${project.property('jackson.version')}"
-}
\ No newline at end of file
+    api libs.net
+    testImplementation libs.jackson.databind
+}
diff --git a/content-resource/src/main/java/module-info.java b/content-resource/src/main/java/module-info.java
index 77b1593..2e54342 100644
--- a/content-resource/src/main/java/module-info.java
+++ b/content-resource/src/main/java/module-info.java
@@ -1,5 +1,5 @@
 module org.xbib.content.resource {
     exports org.xbib.content.resource;
     exports org.xbib.content.resource.text;
-    requires org.xbib.net.url;
-}
\ No newline at end of file
+    requires transitive org.xbib.net.url;
+}
diff --git a/content-resource/src/main/java/org/xbib/content/resource/package-info.java b/content-resource/src/main/java/org/xbib/content/resource/package-info.java
deleted file mode 100644
index 17b9a37..0000000
--- a/content-resource/src/main/java/org/xbib/content/resource/package-info.java
+++ /dev/null
@@ -1,4 +0,0 @@
-/**
- * Classes for content resources (resource identifiers, namespaces, schemes, uniform locations).
- */
-package org.xbib.content.resource;
diff --git a/content-resource/src/main/java/org/xbib/content/resource/text/CodepointIterator.java b/content-resource/src/main/java/org/xbib/content/resource/text/CodepointIterator.java
index 019e3e2..848e004 100644
--- a/content-resource/src/main/java/org/xbib/content/resource/text/CodepointIterator.java
+++ b/content-resource/src/main/java/org/xbib/content/resource/text/CodepointIterator.java
@@ -9,8 +9,12 @@ import java.util.NoSuchElementException;
 public abstract class CodepointIterator implements Iterator<Codepoint> {
 
     protected int position = -1;
+
     protected int limit = -1;
 
+    public CodepointIterator() {
+    }
+
     /**
      * Get a CodepointIterator for the specified char array.
      * @param array char array
diff --git a/content-smile/build.gradle b/content-smile/build.gradle
index 83a2cba..9b1ee1a 100644
--- a/content-smile/build.gradle
+++ b/content-smile/build.gradle
@@ -1,4 +1,4 @@
 dependencies {
     api project(':content-core')
-    api "com.fasterxml.jackson.dataformat:jackson-dataformat-smile:${project.property('jackson.version')}"
+    api libs.jackson.dataformat.smile
 }
diff --git a/content-xml/build.gradle b/content-xml/build.gradle
index 5a39e7b..30e6a64 100644
--- a/content-xml/build.gradle
+++ b/content-xml/build.gradle
@@ -1,7 +1,7 @@
 dependencies {
     api project(':content-core')
     api project(':content-resource')
-    api "com.fasterxml.jackson.dataformat:jackson-dataformat-xml:${project.property('jackson.version')}"
-    runtimeOnly "com.fasterxml.woodstox:woodstox-core:${project.property('woodstox.version')}"
+    api libs.jackson.dataformat.xml
+    runtimeOnly libs.woodstox
     testImplementation project(':content-json') // for XContentHelper reading JSON
 }
diff --git a/content-xml/src/main/java/module-info.java b/content-xml/src/main/java/module-info.java
index 28c5b2a..df7bf89 100644
--- a/content-xml/src/main/java/module-info.java
+++ b/content-xml/src/main/java/module-info.java
@@ -10,6 +10,6 @@ module org.xbib.content.xml {
     requires transitive org.xbib.content.core;
     requires transitive org.xbib.content.resource;
     requires transitive com.fasterxml.jackson.dataformat.xml;
-    requires com.fasterxml.jackson.core;
+    requires transitive com.fasterxml.jackson.core;
     provides XContent with org.xbib.content.xml.XmlXContent;
 }
diff --git a/content-xml/src/main/java/org/xbib/content/xml/json/JsonNamespaceContext.java b/content-xml/src/main/java/org/xbib/content/xml/json/JsonNamespaceContext.java
index e392786..ff80412 100644
--- a/content-xml/src/main/java/org/xbib/content/xml/json/JsonNamespaceContext.java
+++ b/content-xml/src/main/java/org/xbib/content/xml/json/JsonNamespaceContext.java
@@ -4,11 +4,11 @@ import java.util.Iterator;
 
 import javax.xml.namespace.NamespaceContext;
 
-/**
- *
- */
 public class JsonNamespaceContext implements NamespaceContext {
 
+    public JsonNamespaceContext() {
+    }
+
     @Override
     public String getNamespaceURI(String prefix) {
         throw new UnsupportedOperationException();
diff --git a/content-xml/src/main/java/org/xbib/content/xml/json/JsonStylesheet.java b/content-xml/src/main/java/org/xbib/content/xml/json/JsonStylesheet.java
index 3630d1f..3514de4 100644
--- a/content-xml/src/main/java/org/xbib/content/xml/json/JsonStylesheet.java
+++ b/content-xml/src/main/java/org/xbib/content/xml/json/JsonStylesheet.java
@@ -23,7 +23,7 @@ import javax.xml.transform.sax.SAXSource;
  */
 public class JsonStylesheet {
 
-    private QName root = new QName("root");
+    private QName root;
 
     private XmlNamespaceContext context;
 
@@ -31,6 +31,10 @@ public class JsonStylesheet {
 
     private String[] stylesheets;
 
+    public JsonStylesheet() {
+        this.root = new QName("root");
+    }
+
     public JsonStylesheet root(QName root) {
         this.root = root;
         return this;
diff --git a/content-xml/src/main/java/org/xbib/content/xml/json/events/JsonReaderXmlEvent.java b/content-xml/src/main/java/org/xbib/content/xml/json/events/JsonReaderXmlEvent.java
index c095304..93b8d3c 100644
--- a/content-xml/src/main/java/org/xbib/content/xml/json/events/JsonReaderXmlEvent.java
+++ b/content-xml/src/main/java/org/xbib/content/xml/json/events/JsonReaderXmlEvent.java
@@ -8,9 +8,6 @@ import javax.xml.namespace.QName;
 import javax.xml.stream.Location;
 import javax.xml.stream.XMLStreamException;
 
-/**
- *
- */
 public abstract class JsonReaderXmlEvent {
 
     private Location location;
@@ -21,6 +18,9 @@ public abstract class JsonReaderXmlEvent {
 
     private List<Attribute> attributes;
 
+    public JsonReaderXmlEvent() {
+    }
+
     protected void setQName(QName name) {
         this.name = name;
     }
diff --git a/content-xml/src/main/java/org/xbib/content/xml/stream/SimpleNamespaceContext.java b/content-xml/src/main/java/org/xbib/content/xml/stream/SimpleNamespaceContext.java
index 1e60b8d..b77dd3f 100644
--- a/content-xml/src/main/java/org/xbib/content/xml/stream/SimpleNamespaceContext.java
+++ b/content-xml/src/main/java/org/xbib/content/xml/stream/SimpleNamespaceContext.java
@@ -17,12 +17,15 @@ import javax.xml.namespace.NamespaceContext;
  */
 public class SimpleNamespaceContext implements NamespaceContext {
 
-    private Map<String, String> prefixToNamespaceUri = new HashMap<>();
+    private final Map<String, String> prefixToNamespaceUri = new HashMap<>();
 
-    private Map<String, List<String>> namespaceUriToPrefixes = new HashMap<>();
+    private final Map<String, List<String>> namespaceUriToPrefixes = new HashMap<>();
 
     private String defaultNamespaceUri = "";
 
+    public SimpleNamespaceContext() {
+    }
+
     @Override
     public String getNamespaceURI(String prefix) {
         if (XMLConstants.XML_NS_PREFIX.equals(prefix)) {
diff --git a/content-xml/src/main/java/org/xbib/content/xml/stream/XMLFilterImplEx.java b/content-xml/src/main/java/org/xbib/content/xml/stream/XMLFilterImplEx.java
index 979336d..031bcc4 100644
--- a/content-xml/src/main/java/org/xbib/content/xml/stream/XMLFilterImplEx.java
+++ b/content-xml/src/main/java/org/xbib/content/xml/stream/XMLFilterImplEx.java
@@ -13,6 +13,9 @@ public class XMLFilterImplEx extends XMLFilterImpl implements LexicalHandler {
 
     protected boolean namespacePrefixes;
 
+    public XMLFilterImplEx() {
+    }
+
     public boolean getNamespacePrefixes() {
         return namespacePrefixes;
     }
diff --git a/content-xml/src/main/java/org/xbib/content/xml/transform/DefaultStylesheetErrorListener.java b/content-xml/src/main/java/org/xbib/content/xml/transform/DefaultStylesheetErrorListener.java
index 9cbe665..9025e49 100644
--- a/content-xml/src/main/java/org/xbib/content/xml/transform/DefaultStylesheetErrorListener.java
+++ b/content-xml/src/main/java/org/xbib/content/xml/transform/DefaultStylesheetErrorListener.java
@@ -8,6 +8,9 @@ import javax.xml.transform.TransformerException;
  */
 public class DefaultStylesheetErrorListener implements ErrorListener {
 
+    public DefaultStylesheetErrorListener() {
+    }
+
     @Override
     public void warning(TransformerException e) throws TransformerException {
         //logger.log(Level.WARNING, "warning (recoverable): " + e.getMessage(), e);
diff --git a/content-xml/src/main/java/org/xbib/content/xml/transform/StylesheetPool.java b/content-xml/src/main/java/org/xbib/content/xml/transform/StylesheetPool.java
index 9b9d622..5ad269a 100644
--- a/content-xml/src/main/java/org/xbib/content/xml/transform/StylesheetPool.java
+++ b/content-xml/src/main/java/org/xbib/content/xml/transform/StylesheetPool.java
@@ -1,6 +1,5 @@
 package org.xbib.content.xml.transform;
 
-import java.text.MessageFormat;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -21,6 +20,9 @@ public final class StylesheetPool {
      */
     private final Map<String, Templates> stylesheets = new ConcurrentHashMap<>();
 
+    public StylesheetPool() {
+    }
+
     /**
      * @param transformerFactory transformer factory
      * @return returns the identity transformer handler.
diff --git a/content-xml/src/main/java/org/xbib/content/xml/transform/StylesheetTransformer.java b/content-xml/src/main/java/org/xbib/content/xml/transform/StylesheetTransformer.java
index 4ae867e..43bac4c 100644
--- a/content-xml/src/main/java/org/xbib/content/xml/transform/StylesheetTransformer.java
+++ b/content-xml/src/main/java/org/xbib/content/xml/transform/StylesheetTransformer.java
@@ -47,6 +47,9 @@ public class StylesheetTransformer implements Closeable {
 
     private Result result;
 
+    public StylesheetTransformer() {
+    }
+
     public StylesheetTransformer setPath(String... path) {
         if (transformerFactory == null) {
             transformerFactory = (SAXTransformerFactory) TransformerFactory.newInstance();
diff --git a/content-xml/src/main/java/org/xbib/content/xml/transform/TransformerErrorListener.java b/content-xml/src/main/java/org/xbib/content/xml/transform/TransformerErrorListener.java
index d641d0a..fe3eec1 100644
--- a/content-xml/src/main/java/org/xbib/content/xml/transform/TransformerErrorListener.java
+++ b/content-xml/src/main/java/org/xbib/content/xml/transform/TransformerErrorListener.java
@@ -9,6 +9,9 @@ import javax.xml.transform.TransformerException;
  */
 public final class TransformerErrorListener implements ErrorListener {
 
+    public TransformerErrorListener() {
+    }
+
     /**
      * We store the exception internally as a workaround to xalan, which reports
      * {@link javax.xml.transform.TransformerException} as {@link RuntimeException} (wrapped).
diff --git a/content-xml/src/main/java/org/xbib/content/xml/util/XML11Char.java b/content-xml/src/main/java/org/xbib/content/xml/util/XML11Char.java
index dc46ef0..81c5c91 100644
--- a/content-xml/src/main/java/org/xbib/content/xml/util/XML11Char.java
+++ b/content-xml/src/main/java/org/xbib/content/xml/util/XML11Char.java
@@ -36,7 +36,7 @@ public class XML11Char {
     /**
      * Character flags for XML 1.1.
      */
-    private static final byte XML11CHARS[] = new byte[1 << 16];
+    private static final byte[] XML11CHARS = new byte[1 << 16];
 
     static {
         Arrays.fill(XML11CHARS, 1, 9, (byte) 17); // Fill 8 of value (byte) 17
@@ -97,6 +97,9 @@ public class XML11Char {
         Arrays.fill(XML11CHARS, 65008, 65534, (byte) -19); // Fill 526 of value (byte) -19
     }
 
+    public XML11Char() {
+    }
+
     /**
      * Returns true if the specified character is a valid name start
      * character as defined by production [4] in the XML 1.1
diff --git a/content-yaml/build.gradle b/content-yaml/build.gradle
index 0b3f852..7612e11 100644
--- a/content-yaml/build.gradle
+++ b/content-yaml/build.gradle
@@ -1,5 +1,5 @@
 dependencies {
     api project(':content-core')
-    api "com.fasterxml.jackson.dataformat:jackson-dataformat-yaml:${project.property('jackson.version')}"
-    implementation "org.yaml:snakeyaml:${project.property('snakeyaml.version')}"
+    api libs.jackson.dataformat.yaml
+    implementation libs.snakeyaml
 }
diff --git a/content-yaml/src/main/java/org/xbib/content/yaml/YamlXContent.java b/content-yaml/src/main/java/org/xbib/content/yaml/YamlXContent.java
index 00cd87a..a8d93a5 100644
--- a/content-yaml/src/main/java/org/xbib/content/yaml/YamlXContent.java
+++ b/content-yaml/src/main/java/org/xbib/content/yaml/YamlXContent.java
@@ -20,6 +20,7 @@ import java.nio.charset.StandardCharsets;
 public class YamlXContent implements XContent {
 
     private static final YamlXContent yamlXContent;
+
     private static final YAMLFactory yamlFactory;
 
     static {
@@ -27,6 +28,9 @@ public class YamlXContent implements XContent {
         yamlXContent = new YamlXContent();
     }
 
+    public YamlXContent() {
+    }
+
     public static YamlXContent yamlContent() {
         return yamlXContent;
     }
diff --git a/gradle.properties b/gradle.properties
index c75c138..fa97171 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,13 +1,5 @@
 group = org.xbib
 name = content
-version = 4.0.0
+version = 5.0.0
 
 org.gradle.warning.mode = ALL
-gradle.wrapper.version = 7.3.2
-xbib.net.version = 2.1.1
-xbib-datastructures.version = 1.0.0
-jackson.version = 2.12.3
-woodstox.version = 6.2.6
-snakeyaml.version = 1.28
-mockito.version = 3.10.0
-asciidoclet.version = 1.5.6
diff --git a/gradle/quality/spotbugs.gradle b/gradle/quality/spotbugs.gradle
index 2b9e2cf..81b2f63 100644
--- a/gradle/quality/spotbugs.gradle
+++ b/gradle/quality/spotbugs.gradle
@@ -1,6 +1,7 @@
 apply plugin: "com.github.spotbugs"
 
 spotbugs {
+    toolVersion = '4.7.1'
     ignoreFailures = true
 }
 
diff --git a/gradle/test/junit5.gradle b/gradle/test/junit5.gradle
index d3305ec..ce3fc3f 100644
--- a/gradle/test/junit5.gradle
+++ b/gradle/test/junit5.gradle
@@ -1,12 +1,8 @@
-
-def junitVersion = project.hasProperty('junit.version')?project.property('junit.version'):'5.7.2'
-def hamcrestVersion = project.hasProperty('hamcrest.version')?project.property('hamcrest.version'):'2.2'
-
 dependencies {
-    testImplementation "org.junit.jupiter:junit-jupiter-api:${junitVersion}"
-    testImplementation "org.junit.jupiter:junit-jupiter-params:${junitVersion}"
-    testImplementation "org.hamcrest:hamcrest-library:${hamcrestVersion}"
-    testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:${junitVersion}"
+    testImplementation libs.junit.jupiter.api
+    testImplementation libs.junit.jupiter.params
+    testImplementation libs.hamcrest
+    testRuntimeOnly libs.junit.jupiter.engine
 }
 
 test {
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index e708b1c..249e583 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index ac0b842..2ec77e5 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.3.2-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.5-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index 4f906e0..a69d9cb 100755
--- a/gradlew
+++ b/gradlew
@@ -1,7 +1,7 @@
-#!/usr/bin/env sh
+#!/bin/sh
 
 #
-# Copyright 2015 the original author or authors.
+# Copyright © 2015-2021 the original authors.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -17,67 +17,101 @@
 #
 
 ##############################################################################
-##
-##  Gradle start up script for UN*X
-##
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
 ##############################################################################
 
 # Attempt to set APP_HOME
+
 # Resolve links: $0 may be a link
-PRG="$0"
-# Need this for relative symlinks.
-while [ -h "$PRG" ] ; do
-    ls=`ls -ld "$PRG"`
-    link=`expr "$ls" : '.*-> \(.*\)$'`
-    if expr "$link" : '/.*' > /dev/null; then
-        PRG="$link"
-    else
-        PRG=`dirname "$PRG"`"/$link"
-    fi
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
 done
-SAVED="`pwd`"
-cd "`dirname \"$PRG\"`/" >/dev/null
-APP_HOME="`pwd -P`"
-cd "$SAVED" >/dev/null
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
 
 APP_NAME="Gradle"
-APP_BASE_NAME=`basename "$0"`
+APP_BASE_NAME=${0##*/}
 
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
 DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
-MAX_FD="maximum"
+MAX_FD=maximum
 
 warn () {
     echo "$*"
-}
+} >&2
 
 die () {
     echo
     echo "$*"
     echo
     exit 1
-}
+} >&2
 
 # OS specific support (must be 'true' or 'false').
 cygwin=false
 msys=false
 darwin=false
 nonstop=false
-case "`uname`" in
-  CYGWIN* )
-    cygwin=true
-    ;;
-  Darwin* )
-    darwin=true
-    ;;
-  MINGW* )
-    msys=true
-    ;;
-  NONSTOP* )
-    nonstop=true
-    ;;
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
 esac
 
 CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
@@ -87,9 +121,9 @@ CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
 if [ -n "$JAVA_HOME" ] ; then
     if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
         # IBM's JDK on AIX uses strange locations for the executables
-        JAVACMD="$JAVA_HOME/jre/sh/java"
+        JAVACMD=$JAVA_HOME/jre/sh/java
     else
-        JAVACMD="$JAVA_HOME/bin/java"
+        JAVACMD=$JAVA_HOME/bin/java
     fi
     if [ ! -x "$JAVACMD" ] ; then
         die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
@@ -98,7 +132,7 @@ Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
     fi
 else
-    JAVACMD="java"
+    JAVACMD=java
     which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
@@ -106,80 +140,101 @@ location of your Java installation."
 fi
 
 # Increase the maximum file descriptors if we can.
-if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
-    MAX_FD_LIMIT=`ulimit -H -n`
-    if [ $? -eq 0 ] ; then
-        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
-            MAX_FD="$MAX_FD_LIMIT"
-        fi
-        ulimit -n $MAX_FD
-        if [ $? -ne 0 ] ; then
-            warn "Could not set maximum file descriptor limit: $MAX_FD"
-        fi
-    else
-        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
-    fi
-fi
-
-# For Darwin, add options to specify how the application appears in the dock
-if $darwin; then
-    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
-fi
-
-# For Cygwin or MSYS, switch paths to Windows format before running java
-if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
-    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
-    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
-
-    JAVACMD=`cygpath --unix "$JAVACMD"`
-
-    # We build the pattern for arguments to be converted via cygpath
-    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
-    SEP=""
-    for dir in $ROOTDIRSRAW ; do
-        ROOTDIRS="$ROOTDIRS$SEP$dir"
-        SEP="|"
-    done
-    OURCYGPATTERN="(^($ROOTDIRS))"
-    # Add a user-defined pattern to the cygpath arguments
-    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
-        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
-    fi
-    # Now convert the arguments - kludge to limit ourselves to /bin/sh
-    i=0
-    for arg in "$@" ; do
-        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
-        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
-
-        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
-            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
-        else
-            eval `echo args$i`="\"$arg\""
-        fi
-        i=`expr $i + 1`
-    done
-    case $i in
-        0) set -- ;;
-        1) set -- "$args0" ;;
-        2) set -- "$args0" "$args1" ;;
-        3) set -- "$args0" "$args1" "$args2" ;;
-        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
 fi
 
-# Escape application args
-save () {
-    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
-    echo " "
-}
-APP_ARGS=`save "$@"`
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
 
-# Collect all arguments for the java command, following the shell quoting and substitution rules
-eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
 
 exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
index ac1b06f..53a6b23 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -14,7 +14,7 @@
 @rem limitations under the License.
 @rem
 
-@if "%DEBUG%" == "" @echo off
+@if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
 @rem  Gradle startup script for Windows
@@ -25,7 +25,7 @@
 if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
+if "%DIRNAME%"=="" set DIRNAME=.
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
@@ -40,7 +40,7 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto execute
+if %ERRORLEVEL% equ 0 goto execute
 
 echo.
 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
@@ -75,13 +75,15 @@ set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
 :end
 @rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
+if %ERRORLEVEL% equ 0 goto mainEnd
 
 :fail
 rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
 rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
 
 :mainEnd
 if "%OS%"=="Windows_NT" endlocal
diff --git a/settings-api/build.gradle b/settings-api/build.gradle
index aed7a6e..5c6af21 100644
--- a/settings-api/build.gradle
+++ b/settings-api/build.gradle
@@ -1,3 +1,3 @@
 dependencies {
-    api "org.xbib:datastructures-api:${project.property('xbib-datastructures.version')}"
-}
\ No newline at end of file
+    api libs.datastructures.api
+}
diff --git a/settings-api/src/main/java/org/xbib/settings/Settings.java b/settings-api/src/main/java/org/xbib/settings/Settings.java
index 24f2778..a9af55f 100644
--- a/settings-api/src/main/java/org/xbib/settings/Settings.java
+++ b/settings-api/src/main/java/org/xbib/settings/Settings.java
@@ -11,6 +11,9 @@ public interface Settings extends AutoCloseable {
 
     class Holder {
 
+        private Holder() {
+        }
+
         private static SettingsBuilder createBuilder() {
             ServiceLoader<SettingsBuilder> serviceLoader = ServiceLoader.load(SettingsBuilder.class);
             Optional<SettingsBuilder> optionalSettingsBuilder = serviceLoader.findFirst();
diff --git a/settings-content-json/src/main/java/module-info.java b/settings-content-json/src/main/java/module-info.java
index d70cab8..1d84675 100644
--- a/settings-content-json/src/main/java/module-info.java
+++ b/settings-content-json/src/main/java/module-info.java
@@ -4,8 +4,7 @@ import org.xbib.settings.content.json.JsonSettingsLoader;
 module org.xbib.settings.content.json {
     exports org.xbib.settings.content.json;
     requires transitive org.xbib.settings.content;
-    requires org.xbib.content.api;
-    requires org.xbib.content.json;
+    requires transitive org.xbib.content.json;
     requires org.xbib.settings.api;
     uses SettingsLoader;
     provides SettingsLoader with JsonSettingsLoader;
diff --git a/settings-content-json/src/main/java/org/xbib/settings/content/json/JsonSettingsLoader.java b/settings-content-json/src/main/java/org/xbib/settings/content/json/JsonSettingsLoader.java
index cfd4280..99542a4 100644
--- a/settings-content-json/src/main/java/org/xbib/settings/content/json/JsonSettingsLoader.java
+++ b/settings-content-json/src/main/java/org/xbib/settings/content/json/JsonSettingsLoader.java
@@ -11,6 +11,9 @@ import java.util.Set;
  */
 public class JsonSettingsLoader extends AbstractSettingsLoader {
 
+    public JsonSettingsLoader() {
+    }
+
     @Override
     public XContent content() {
         return JsonXContent.jsonContent();
diff --git a/settings-content-yaml/src/main/java/module-info.java b/settings-content-yaml/src/main/java/module-info.java
index e0ba9df..088eed1 100644
--- a/settings-content-yaml/src/main/java/module-info.java
+++ b/settings-content-yaml/src/main/java/module-info.java
@@ -4,8 +4,7 @@ import org.xbib.settings.content.yaml.YamlSettingsLoader;
 module org.xbib.settings.content.yaml {
     exports org.xbib.settings.content.yaml;
     requires transitive org.xbib.settings.content;
-    requires org.xbib.content.api;
-    requires org.xbib.content.yaml;
+    requires transitive org.xbib.content.yaml;
     requires org.xbib.settings.api;
     uses SettingsLoader;
     provides SettingsLoader with YamlSettingsLoader;
diff --git a/settings-content-yaml/src/main/java/org/xbib/settings/content/yaml/YamlSettingsLoader.java b/settings-content-yaml/src/main/java/org/xbib/settings/content/yaml/YamlSettingsLoader.java
index 5e07789..4ca797f 100644
--- a/settings-content-yaml/src/main/java/org/xbib/settings/content/yaml/YamlSettingsLoader.java
+++ b/settings-content-yaml/src/main/java/org/xbib/settings/content/yaml/YamlSettingsLoader.java
@@ -15,6 +15,9 @@ public class YamlSettingsLoader extends AbstractSettingsLoader {
 
     private static final Set<String> YAML_SUFFIXES = Set.of("yml", "yaml");
 
+    public YamlSettingsLoader() {
+    }
+
     @Override
     public XContent content() {
         return YamlXContent.yamlContent();
diff --git a/settings-content/build.gradle b/settings-content/build.gradle
index 80c36e4..3c281a7 100644
--- a/settings-content/build.gradle
+++ b/settings-content/build.gradle
@@ -1,6 +1,6 @@
 dependencies {
     api project(':settings-api')
     api project(':content-core')
-    api "org.xbib:datastructures-tiny:${project.property('xbib-datastructures.version')}"
+    api libs.datastructures.tiny
     testImplementation project(":settings-content-json")
 }
diff --git a/settings-content/src/main/java/module-info.java b/settings-content/src/main/java/module-info.java
index cef58ab..2d8013d 100644
--- a/settings-content/src/main/java/module-info.java
+++ b/settings-content/src/main/java/module-info.java
@@ -9,8 +9,7 @@ module org.xbib.settings.content {
     uses SettingsBuilder;
     provides SettingsBuilder with ContentSettingsBuilder;
     exports org.xbib.settings.content;
-    requires org.xbib.settings.api;
-    requires org.xbib.content.core;
-    requires org.xbib.datastructures.api;
+    requires transitive org.xbib.settings.api;
+    requires transitive org.xbib.content.core;
     requires transitive org.xbib.datastructures.tiny;
 }
diff --git a/settings-content/src/main/java/org/xbib/settings/content/AbstractSettingsLoader.java b/settings-content/src/main/java/org/xbib/settings/content/AbstractSettingsLoader.java
index 139d217..34f7a6c 100644
--- a/settings-content/src/main/java/org/xbib/settings/content/AbstractSettingsLoader.java
+++ b/settings-content/src/main/java/org/xbib/settings/content/AbstractSettingsLoader.java
@@ -20,6 +20,9 @@ import java.util.Map;
  */
 public abstract class AbstractSettingsLoader implements SettingsLoader {
 
+    public AbstractSettingsLoader() {
+    }
+
     public abstract XContent content();
 
     @Override
diff --git a/settings-content/src/main/java/org/xbib/settings/content/PropertiesSettingsLoader.java b/settings-content/src/main/java/org/xbib/settings/content/PropertiesSettingsLoader.java
index f101291..a1889b2 100644
--- a/settings-content/src/main/java/org/xbib/settings/content/PropertiesSettingsLoader.java
+++ b/settings-content/src/main/java/org/xbib/settings/content/PropertiesSettingsLoader.java
@@ -21,6 +21,9 @@ public class PropertiesSettingsLoader implements SettingsLoader {
 
     private static final Set<String> PROPERTIES_SUFFIXES = new HashSet<>(Collections.singletonList("properties"));
 
+    public PropertiesSettingsLoader() {
+    }
+
     @Override
     public Set<String> suffixes() {
         return PROPERTIES_SUFFIXES;
diff --git a/settings-datastructures-json/build.gradle b/settings-datastructures-json/build.gradle
index 6382f07..3337978 100644
--- a/settings-datastructures-json/build.gradle
+++ b/settings-datastructures-json/build.gradle
@@ -1,4 +1,4 @@
 dependencies {
     api project(':settings-datastructures')
-    api "org.xbib:datastructures-json-tiny:${project.property('xbib-datastructures.version')}"
+    api libs.datastructures.json.tiny
 }
diff --git a/settings-datastructures-json/src/main/java/org/xbib/settings/datastructures/json/JsonSettingsLoader.java b/settings-datastructures-json/src/main/java/org/xbib/settings/datastructures/json/JsonSettingsLoader.java
index 987e33a..b023e99 100644
--- a/settings-datastructures-json/src/main/java/org/xbib/settings/datastructures/json/JsonSettingsLoader.java
+++ b/settings-datastructures-json/src/main/java/org/xbib/settings/datastructures/json/JsonSettingsLoader.java
@@ -7,6 +7,9 @@ import java.util.Set;
 
 public class JsonSettingsLoader extends AbstractSettingsLoader {
 
+    public JsonSettingsLoader() {
+    }
+
     @Override
     public DataStructure dataStructure() {
         return new Json();
diff --git a/settings-datastructures-yaml/build.gradle b/settings-datastructures-yaml/build.gradle
index 79a0278..d6f34d6 100644
--- a/settings-datastructures-yaml/build.gradle
+++ b/settings-datastructures-yaml/build.gradle
@@ -1,4 +1,4 @@
 dependencies {
     api project(':settings-datastructures')
-    api "org.xbib:datastructures-yaml-tiny:${project.property('xbib-datastructures.version')}"
+    api libs.datastructures.yaml.tiny
 }
diff --git a/settings-datastructures-yaml/src/main/java/org/xbib/settings/datastructures/yaml/YamlSettingsLoader.java b/settings-datastructures-yaml/src/main/java/org/xbib/settings/datastructures/yaml/YamlSettingsLoader.java
index 3716cc3..11647a7 100644
--- a/settings-datastructures-yaml/src/main/java/org/xbib/settings/datastructures/yaml/YamlSettingsLoader.java
+++ b/settings-datastructures-yaml/src/main/java/org/xbib/settings/datastructures/yaml/YamlSettingsLoader.java
@@ -10,6 +10,9 @@ import java.util.Set;
 
 public class YamlSettingsLoader extends AbstractSettingsLoader {
 
+    public YamlSettingsLoader() {
+    }
+
     @Override
     public DataStructure dataStructure() {
         return new Yaml();
diff --git a/settings-datastructures/build.gradle b/settings-datastructures/build.gradle
index a5efeea..1007c01 100644
--- a/settings-datastructures/build.gradle
+++ b/settings-datastructures/build.gradle
@@ -1,4 +1,4 @@
 dependencies {
     api project(':settings-api')
-    api "org.xbib:datastructures-tiny:${project.property('xbib-datastructures.version')}"
+    api libs.datastructures.tiny
 }
diff --git a/settings-datastructures/src/main/java/org/xbib/settings/datastructures/AbstractSettingsLoader.java b/settings-datastructures/src/main/java/org/xbib/settings/datastructures/AbstractSettingsLoader.java
index 0149290..96b182a 100644
--- a/settings-datastructures/src/main/java/org/xbib/settings/datastructures/AbstractSettingsLoader.java
+++ b/settings-datastructures/src/main/java/org/xbib/settings/datastructures/AbstractSettingsLoader.java
@@ -19,6 +19,9 @@ import java.util.Map;
 
 public abstract class AbstractSettingsLoader implements SettingsLoader {
 
+    public AbstractSettingsLoader() {
+    }
+
     public abstract DataStructure dataStructure();
 
     @Override
diff --git a/settings-datastructures/src/main/java/org/xbib/settings/datastructures/PropertiesSettingsLoader.java b/settings-datastructures/src/main/java/org/xbib/settings/datastructures/PropertiesSettingsLoader.java
index bed385e..7e21857 100644
--- a/settings-datastructures/src/main/java/org/xbib/settings/datastructures/PropertiesSettingsLoader.java
+++ b/settings-datastructures/src/main/java/org/xbib/settings/datastructures/PropertiesSettingsLoader.java
@@ -13,6 +13,9 @@ import java.util.Set;
  */
 public class PropertiesSettingsLoader implements SettingsLoader {
 
+    public PropertiesSettingsLoader() {
+    }
+
     @Override
     public Set<String> suffixes() {
         return Set.of("properties");
diff --git a/settings.gradle b/settings.gradle
index 457a20f..090e126 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1,3 +1,32 @@
+dependencyResolutionManagement {
+    versionCatalogs {
+        libs {
+            version('gradle', '7.5')
+            version('junit', '5.8.2')
+            version('jackson', '2.13.3')
+            version('datastructures', '1.0.0')
+            library('junit-jupiter-api', 'org.junit.jupiter', 'junit-jupiter-api').versionRef('junit')
+            library('junit-jupiter-params', 'org.junit.jupiter', 'junit-jupiter-params').versionRef('junit')
+            library('junit-jupiter-engine', 'org.junit.jupiter', 'junit-jupiter-engine').versionRef('junit')
+            library('junit4', 'junit', 'junit').version('4.13.2')
+            library('hamcrest', 'org.hamcrest:hamcrest-library:2.2')
+            library('jackson-core', 'com.fasterxml.jackson.core', 'jackson-core').versionRef('jackson')
+            library('jackson-databind', 'com.fasterxml.jackson.core', 'jackson-databind').versionRef('jackson')
+            library('jackson-dataformat-smile', 'com.fasterxml.jackson.dataformat', 'jackson-dataformat-smile').versionRef('jackson')
+            library('jackson-dataformat-xml', 'com.fasterxml.jackson.dataformat', 'jackson-dataformat-xml').versionRef('jackson')
+            library('jackson-dataformat-yaml', 'com.fasterxml.jackson.dataformat', 'jackson-dataformat-yaml').versionRef('jackson')
+            library('datastructures-api', 'org.xbib', 'datastructures-api').versionRef('datastructures')
+            library('datastructures-tiny', 'org.xbib', 'datastructures-tiny').versionRef('datastructures')
+            library('datastructures-json-tiny', 'org.xbib', 'datastructures-json-tiny').versionRef('datastructures')
+            library('datastructures-yaml-tiny', 'org.xbib', 'datastructures-yaml-tiny').versionRef('datastructures')
+            library('mockito-core', 'org.mockito', 'mockito-core').version('4.6.1')
+            library('mockito-inline', 'org.mockito', 'mockito-inline').version('4.6.1')
+            library('net', 'org.xbib', 'net-url').version('2.1.1')
+            library('woodstox', 'com.fasterxml.woodstox', 'woodstox-core').version('6.3.0')
+            library('snakeyaml', 'org.yaml', 'snakeyaml').version('1.30')
+        }
+    }
+}
 include 'content-api'
 include 'content-core'
 include 'content-csv'
@@ -16,3 +45,14 @@ include 'settings-datastructures'
 include 'settings-datastructures-json'
 include 'settings-datastructures-yaml'
 include 'config'
+
+/*
+gradle.wrapper.version = 7.4.2
+xbib.net.version = 2.1.1
+xbib-datastructures.version = 1.0.0
+jackson.version = 2.12.3
+woodstox.version = 6.2.6
+snakeyaml.version = 1.28
+mockito.version = 3.10.0
+asciidoclet.version = 1.5.6
+ */
\ No newline at end of file