diff --git a/settings.gradle b/settings.gradle
index 6bfcf2e..bb7cef1 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -10,7 +10,7 @@ dependencyResolutionManagement {
             library('junit-jupiter-engine', 'org.junit.jupiter', 'junit-jupiter-engine').versionRef('junit')
             library('hamcrest', 'org.hamcrest', 'hamcrest-library').version('2.2')
             library('charactersets', 'org.xbib', 'bibliographic-character-sets').version('2.0.0')
-            library('json', 'org.xbib', 'content-json').version('4.0.0')
+            library('json', 'org.xbib', 'content-json').version('5.0.1')
             library('xalan', 'xalan', 'xalan').version('2.7.2')
             library('xmlunit', 'org.xmlunit', 'xmlunit-matchers').version('2.8.4')
             library('mockito', 'org.mockito', 'mockito-core').version('3.3.3')
diff --git a/src/main/java/org/xbib/marc/MarcRecord.java b/src/main/java/org/xbib/marc/MarcRecord.java
index d588e0f..90123cc 100644
--- a/src/main/java/org/xbib/marc/MarcRecord.java
+++ b/src/main/java/org/xbib/marc/MarcRecord.java
@@ -22,7 +22,6 @@ import static org.xbib.marc.json.MarcJsonWriter.TYPE_TAG;
 import org.xbib.marc.label.RecordLabel;
 
 import java.util.Collection;
-import java.util.Deque;
 import java.util.LinkedHashMap;
 import java.util.LinkedList;
 import java.util.List;
@@ -31,8 +30,6 @@ import java.util.Set;
 import java.util.TreeMap;
 import java.util.function.BiConsumer;
 import java.util.function.Predicate;
-import java.util.logging.Level;
-import java.util.logging.Logger;
 import java.util.regex.Pattern;
 
 /**