diff --git a/build.gradle b/build.gradle
index 01001d2..678c7e7 100644
--- a/build.gradle
+++ b/build.gradle
@@ -3,10 +3,10 @@ plugins {
     id "pmd"
     id 'maven-publish'
     id 'signing'
-    id "io.github.gradle-nexus.publish-plugin" version "1.3.0"
-    id "com.github.spotbugs" version "5.0.14"
-    id "org.cyclonedx.bom" version "1.7.2"
-    id "org.xbib.gradle.plugin.asciidoctor" version "2.5.2.2"
+    id "io.github.gradle-nexus.publish-plugin" version "2.0.0-rc-1"
+   // id "com.github.spotbugs" version "6.0.0-beta.3"
+    id "org.cyclonedx.bom" version "1.7.4"
+    id "org.xbib.gradle.plugin.asciidoctor" version "3.0.0"
 }
 
 wrapper {
@@ -29,13 +29,13 @@ ext {
     licenseUrl = 'http://www.apache.org/licenses/LICENSE-2.0.txt'
 }
 
-apply from: rootProject.file('gradle/ide/idea.gradle')
+//apply from: rootProject.file('gradle/ide/idea.gradle')
 apply from: rootProject.file('gradle/repositories/maven.gradle')
 apply from: rootProject.file('gradle/compile/java.gradle')
 apply from: rootProject.file('gradle/test/junit5.gradle')
 apply from: rootProject.file('gradle/quality/checkstyle.gradle')
 apply from: rootProject.file('gradle/quality/pmd.gradle')
-apply from: rootProject.file('gradle/quality/spotbugs.gradle')
+//apply from: rootProject.file('gradle/quality/spotbugs.gradle')
 apply from: rootProject.file('gradle/publish/maven.gradle')
 apply from: rootProject.file('gradle/publish/forgejo.gradle')
 apply from: rootProject.file('gradle/publish/sonatype.gradle')
@@ -43,5 +43,6 @@ apply from: rootProject.file('gradle/publish/sonatype.gradle')
 dependencies {
     testImplementation libs.quartz
     testImplementation libs.caliper
+    testImplementation libs.guava
 }
 
diff --git a/gradle.properties b/gradle.properties
index 4ad2d3e..e76a622 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,5 +1,5 @@
 group = org.xbib
 name = time
-version = 3.0.0
+version = 4.0.0
 
 org.gradle.warning.mode = ALL
diff --git a/gradle/compile/java.gradle b/gradle/compile/java.gradle
index a37f057..c686724 100644
--- a/gradle/compile/java.gradle
+++ b/gradle/compile/java.gradle
@@ -2,21 +2,14 @@
 apply plugin: 'java-library'
 
 java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(21)
+    }
     modularity.inferModulePath.set(true)
     withSourcesJar()
     withJavadocJar()
 }
 
-compileJava {
-    sourceCompatibility = JavaVersion.VERSION_17
-    targetCompatibility = JavaVersion.VERSION_17
-}
-
-compileTestJava {
-    sourceCompatibility = JavaVersion.VERSION_17
-    targetCompatibility = JavaVersion.VERSION_17
-}
-
 jar {
     manifest {
         attributes('Implementation-Version': project.version)
@@ -24,9 +17,13 @@ jar {
 }
 
 tasks.withType(JavaCompile) {
-    options.compilerArgs << '-Xlint:all,-fallthrough'
+    options.fork = true
+    options.forkOptions.jvmArgs += ['-Duser.language=en','-Duser.country=US']
+    options.compilerArgs << '-Xlint:all'
+    options.encoding = 'UTF-8'
 }
 
 javadoc {
     options.addStringOption('Xdoclint:none', '-quiet')
+    options.encoding = 'UTF-8'
 }
diff --git a/gradle/test/junit5.gradle b/gradle/test/junit5.gradle
index 09ce233..74ec48c 100644
--- a/gradle/test/junit5.gradle
+++ b/gradle/test/junit5.gradle
@@ -3,6 +3,7 @@ dependencies {
     testImplementation libs.junit.jupiter.params
     testImplementation libs.hamcrest
     testRuntimeOnly libs.junit.jupiter.engine
+    testRuntimeOnly libs.junit.jupiter.platform.launcher
 }
 
 test {
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index c1962a7..7f93135 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 8707e8b..8838ba9 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.1.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-all.zip
 networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index aeb74cb..1aa94a4 100755
--- a/gradlew
+++ b/gradlew
@@ -83,7 +83,8 @@ done
 # This is normally unused
 # shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -130,10 +131,13 @@ location of your Java installation."
     fi
 else
     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.
+    if ! command -v java >/dev/null 2>&1
+    then
+        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
 location of your Java installation."
+    fi
 fi
 
 # Increase the maximum file descriptors if we can.
@@ -141,7 +145,7 @@ if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
         # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
-        # shellcheck disable=SC3045
+        # shellcheck disable=SC2039,SC3045
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
@@ -149,7 +153,7 @@ if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
       '' | soft) :;; #(
       *)
         # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
-        # shellcheck disable=SC3045
+        # shellcheck disable=SC2039,SC3045
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -198,11 +202,11 @@ fi
 # 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"'
 
-# 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.
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
diff --git a/settings.gradle b/settings.gradle
index faf8652..faa2759 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1,16 +1,18 @@
 dependencyResolutionManagement {
     versionCatalogs {
         libs {
-            version('gradle', '8.1.1')
-            version('groovy', '3.0.15')
-            version('junit', '5.9.3')
+            version('gradle', '8.4')
+            version('groovy', '3.0.17')
+            version('junit', '5.10.0')
             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('junit-jupiter-platform-launcher', 'org.junit.platform', 'junit-platform-launcher').version('1.10.0')
             library('hamcrest', 'org.hamcrest', 'hamcrest-library').version('2.2')
             library('junit4', 'junit', 'junit').version('4.13.2')
             library('quartz', 'org.quartz-scheduler', 'quartz').version('2.3.2')
             library('caliper',  'com.google.caliper', 'caliper').version('1.0-beta-3')
+            library('guava', 'com.google.guava', 'guava').version('32.1.3-jre')
         }
     }
 }
diff --git a/src/test/java/org/xbib/time/schedule/KeywordsTest.java b/src/test/java/org/xbib/time/schedule/KeywordsTest.java
index 2fc75d6..5f15906 100644
--- a/src/test/java/org/xbib/time/schedule/KeywordsTest.java
+++ b/src/test/java/org/xbib/time/schedule/KeywordsTest.java
@@ -53,7 +53,7 @@ public class KeywordsTest {
             keywords.put("", 0);
             fail("Expected exception");
         } catch (StringIndexOutOfBoundsException e) {
-            assertEquals("String index out of range: 0", e.getMessage());
+            assertEquals("Index 0 out of bounds for length 0", e.getMessage());
         }
     }
 
@@ -63,7 +63,7 @@ public class KeywordsTest {
             keywords.put("A", 0);
             fail("Expected exception");
         } catch (StringIndexOutOfBoundsException e) {
-            assertEquals("String index out of range: 1", e.getMessage());
+            assertEquals("Index 1 out of bounds for length 1", e.getMessage());
         }
     }
 
diff --git a/src/test/java/org/xbib/time/schedule/util/ObjectSizeCalculator.java b/src/test/java/org/xbib/time/schedule/util/ObjectSizeCalculator.java
index 5cca08d..5841f05 100644
--- a/src/test/java/org/xbib/time/schedule/util/ObjectSizeCalculator.java
+++ b/src/test/java/org/xbib/time/schedule/util/ObjectSizeCalculator.java
@@ -113,16 +113,12 @@ public class ObjectSizeCalculator {
     // added.
     private final int superclassFieldPadding;
 
-    private final LoadingCache<Class<?>, ClassSizeInfo> classSizeInfos =
-            CacheBuilder.newBuilder().build(new CacheLoader<Class<?>, ClassSizeInfo>() {
-                public ClassSizeInfo load(Class<?> clazz) {
-                    return new ClassSizeInfo(clazz);
-                }
-            });
+    private final LoadingCache<Class<?>, ClassSizeInfo> classSizeInfos;
 
+    private final Set<Object> alreadyVisited;
+
+    private final Deque<Object> pending;
 
-    private final Set<Object> alreadyVisited = Sets.newIdentityHashSet();
-    private final Deque<Object> pending = new ArrayDeque<Object>(16 * 1024);
     private long size;
 
     /**
@@ -138,6 +134,13 @@ public class ObjectSizeCalculator {
         objectPadding = memoryLayoutSpecification.getObjectPadding();
         referenceSize = memoryLayoutSpecification.getReferenceSize();
         superclassFieldPadding = memoryLayoutSpecification.getSuperclassFieldPadding();
+        classSizeInfos = CacheBuilder.newBuilder().build(new CacheLoader<>() {
+            public ClassSizeInfo load(Class<?> clazz) {
+                return new ClassSizeInfo(clazz);
+            }
+        });
+        alreadyVisited = Sets.newIdentityHashSet();
+        pending = new ArrayDeque<>(16 * 1024);
     }
 
     /**
@@ -262,7 +265,7 @@ public class ObjectSizeCalculator {
 
         public ClassSizeInfo(Class<?> clazz) {
             long fieldsSize = 0;
-            final List<Field> referenceFields = new LinkedList<Field>();
+            final List<Field> referenceFields = new LinkedList<>();
             for (Field f : clazz.getDeclaredFields()) {
                 if (Modifier.isStatic(f.getModifiers())) {
                     continue;
@@ -284,8 +287,7 @@ public class ObjectSizeCalculator {
             }
             this.fieldsSize = fieldsSize;
             this.objectSize = roundTo(objectHeaderSize + fieldsSize, objectPadding);
-            this.referenceFields = referenceFields.toArray(
-                    new Field[referenceFields.size()]);
+            this.referenceFields = referenceFields.toArray(new Field[0]);
         }
 
         void visit(Object obj, ObjectSizeCalculator calc) {
@@ -298,9 +300,7 @@ public class ObjectSizeCalculator {
                 try {
                     calc.enqueue(f.get(obj));
                 } catch (IllegalAccessException e) {
-                    final AssertionError ae = new AssertionError(
-                            "Unexpected denial of access to " + f, e);
-                    throw ae;
+                    throw new AssertionError("Unexpected denial of access to " + f, e);
                 }
             }
         }
@@ -327,10 +327,8 @@ public class ObjectSizeCalculator {
     static MemoryLayoutSpecification getEffectiveMemoryLayoutSpecification() {
         final String vmName = System.getProperty("java.vm.name");
         if (vmName == null || !(vmName.startsWith("Java HotSpot(TM) ") || vmName.startsWith("OpenJDK"))) {
-            throw new UnsupportedOperationException(
-                    "ObjectSizeCalculator only supported on HotSpot VM");
+            throw new UnsupportedOperationException("ObjectSizeCalculator only supported on HotSpot VM");
         }
-
         final String dataModel = System.getProperty("sun.arch.data.model");
         if ("32".equals(dataModel)) {
             // Running with 32-bit data model
@@ -364,10 +362,17 @@ public class ObjectSizeCalculator {
             throw new UnsupportedOperationException("Unrecognized value '" +
                     dataModel + "' of sun.arch.data.model system property");
         }
-
         final String strVmVersion = System.getProperty("java.vm.version");
-        final int vmVersion = Integer.parseInt(strVmVersion.substring(0,
-                strVmVersion.indexOf('.')));
+        if (strVmVersion == null) {
+            throw new UnsupportedOperationException("property java.vm.version does not exist");
+        }
+        int pos = strVmVersion.indexOf('.');
+        pos = pos > 0 ? pos : strVmVersion.length();
+        if (pos == strVmVersion.length()) {
+            pos = strVmVersion.indexOf('+');
+            pos = pos > 0 ? pos : strVmVersion.length();
+        }
+        final int vmVersion = Integer.parseInt(strVmVersion.substring(0, pos));
         if (vmVersion >= 17) {
             long maxMemory = 0;
             for (MemoryPoolMXBean mp : ManagementFactory.getMemoryPoolMXBeans()) {