diff --git a/community/kernel/src/main/java/org/neo4j/kernel/CommunityIdTypeConfigurationProvider.java b/community/kernel/src/main/java/org/neo4j/kernel/CommunityIdTypeConfigurationProvider.java
index e5c939e890ec5..10fecee209ac9 100644
--- a/community/kernel/src/main/java/org/neo4j/kernel/CommunityIdTypeConfigurationProvider.java
+++ b/community/kernel/src/main/java/org/neo4j/kernel/CommunityIdTypeConfigurationProvider.java
@@ -33,8 +33,8 @@
 public class CommunityIdTypeConfigurationProvider implements IdTypeConfigurationProvider
 {
 
-    private Map<IdType,IdTypeConfiguration> typeConfigurations = new EnumMap<>(IdType.class);
-    private Set<IdType> typesToAllowReuse = EnumSet.of( IdType.PROPERTY, IdType.STRING_BLOCK,
+    private final Map<IdType,IdTypeConfiguration> typeConfigurations = new EnumMap<>(IdType.class);
+    private final Set<IdType> typesToAllowReuse = EnumSet.of( IdType.PROPERTY, IdType.STRING_BLOCK,
             IdType.ARRAY_BLOCK, IdType.NODE_LABELS);
 
     @Override
diff --git a/community/kernel/src/main/java/org/neo4j/kernel/DefaultIdGeneratorFactory.java b/community/kernel/src/main/java/org/neo4j/kernel/DefaultIdGeneratorFactory.java
index deed68d7330e7..962390e51b8a6 100644
--- a/community/kernel/src/main/java/org/neo4j/kernel/DefaultIdGeneratorFactory.java
+++ b/community/kernel/src/main/java/org/neo4j/kernel/DefaultIdGeneratorFactory.java
@@ -53,8 +53,7 @@ public DefaultIdGeneratorFactory( FileSystemAbstraction fs, IdTypeConfigurationP
     public IdGenerator open( File filename, IdType idType, long highId )
     {
         IdTypeConfiguration idTypeConfiguration = idTypeConfigurationProvider.getIdTypeConfiguration( idType );
-        return  open( filename, idTypeConfiguration.getGrabSize(), idType,
-                idTypeConfiguration.allowAggressiveReuse(), highId );
+        return open( filename, idTypeConfiguration.getGrabSize(), idType, idTypeConfiguration.allowAggressiveReuse(), highId );
     }
 
     public IdGenerator open( File fileName, int grabSize, IdType idType, long highId )
diff --git a/community/kernel/src/main/java/org/neo4j/kernel/IdGeneratorFactory.java b/community/kernel/src/main/java/org/neo4j/kernel/IdGeneratorFactory.java
index 14c0c73a0c3e6..1b350c0d3742c 100644
--- a/community/kernel/src/main/java/org/neo4j/kernel/IdGeneratorFactory.java
+++ b/community/kernel/src/main/java/org/neo4j/kernel/IdGeneratorFactory.java
@@ -38,37 +38,4 @@ public interface IdGeneratorFactory
 
     IdGenerator get( IdType idType );
 
-    class Delegate implements IdGeneratorFactory
-    {
-        private final IdGeneratorFactory delegate;
-
-        public Delegate( IdGeneratorFactory delegate )
-        {
-            this.delegate = delegate;
-        }
-
-        @Override
-        public IdGenerator open( File filename, IdType idType, long highId )
-        {
-            return delegate.open( filename, idType, highId );
-        }
-
-        @Override
-        public IdGenerator open( File filename, int grabSize, IdType idType, long highId )
-        {
-            return delegate.open( filename, grabSize, idType, highId );
-        }
-
-        @Override
-        public void create( File filename, long highId, boolean throwIfFileExists )
-        {
-            delegate.create( filename, highId, throwIfFileExists );
-        }
-
-        @Override
-        public IdGenerator get( IdType idType )
-        {
-            return delegate.get( idType );
-        }
-    }
 }
diff --git a/community/kernel/src/main/java/org/neo4j/kernel/IdTypeConfiguration.java b/community/kernel/src/main/java/org/neo4j/kernel/IdTypeConfiguration.java
index a1e4b5584fa71..7326119b60484 100644
--- a/community/kernel/src/main/java/org/neo4j/kernel/IdTypeConfiguration.java
+++ b/community/kernel/src/main/java/org/neo4j/kernel/IdTypeConfiguration.java
@@ -26,7 +26,7 @@
  */
 public class IdTypeConfiguration
 {
-    private boolean allowAggressiveReuse;
+    private final boolean allowAggressiveReuse;
 
     public IdTypeConfiguration( boolean allowAggressiveReuse )
     {
diff --git a/community/kernel/src/main/java/org/neo4j/kernel/impl/store/id/BufferingIdGeneratorFactory.java b/community/kernel/src/main/java/org/neo4j/kernel/impl/store/id/BufferingIdGeneratorFactory.java
index 0317ba4ffa4c9..4f2c8d53cf628 100644
--- a/community/kernel/src/main/java/org/neo4j/kernel/impl/store/id/BufferingIdGeneratorFactory.java
+++ b/community/kernel/src/main/java/org/neo4j/kernel/impl/store/id/BufferingIdGeneratorFactory.java
@@ -34,17 +34,19 @@
  * so that ids can be {@link IdGenerator#freeId(long) freed} at safe points in time, after all transactions
  * which were active at the time of freeing, have been closed.
  */
-public class BufferingIdGeneratorFactory extends IdGeneratorFactory.Delegate
+public class BufferingIdGeneratorFactory implements IdGeneratorFactory
 {
     private final BufferingIdGenerator[/*IdType#ordinal as key*/] overriddenIdGenerators =
             new BufferingIdGenerator[IdType.values().length];
     private Supplier<KernelTransactionsSnapshot> boundaries;
     private Predicate<KernelTransactionsSnapshot> safeThreshold;
-    private IdTypeConfigurationProvider idTypeConfigurationProvider;
+    private final IdGeneratorFactory delegate;
+    private final IdTypeConfigurationProvider idTypeConfigurationProvider;
 
-    public BufferingIdGeneratorFactory( IdGeneratorFactory delegate, IdTypeConfigurationProvider idTypeConfigurationProvider )
+    public BufferingIdGeneratorFactory( IdGeneratorFactory delegate,
+            IdTypeConfigurationProvider idTypeConfigurationProvider )
     {
-        super( delegate );
+        this.delegate = delegate;
         this.idTypeConfigurationProvider = idTypeConfigurationProvider;
     }
 
@@ -68,10 +70,17 @@ public boolean test( KernelTransactionsSnapshot snapshot )
         }
     }
 
+    @Override
+    public IdGenerator open( File filename, IdType idType, long highId )
+    {
+        IdTypeConfiguration typeConfiguration = idTypeConfigurationProvider.getIdTypeConfiguration( idType );
+        return open( filename, typeConfiguration.getGrabSize(), idType, highId);
+    }
+
     @Override
     public IdGenerator open( File filename, int grabSize, IdType idType, long highId )
     {
-        IdGenerator generator = super.open( filename, grabSize, idType, highId );
+        IdGenerator generator = delegate.open( filename, grabSize, idType, highId );
         IdTypeConfiguration typeConfiguration = getIdTypeConfiguration(idType);
         if ( typeConfiguration.allowAggressiveReuse() )
         {
@@ -103,6 +112,12 @@ public IdGenerator open( File filename, int grabSize, IdType idType, long highId
         return generator;
     }
 
+    @Override
+    public void create( File filename, long highId, boolean throwIfFileExists )
+    {
+        delegate.create( filename, highId, throwIfFileExists );
+    }
+
     private IdTypeConfiguration getIdTypeConfiguration( IdType idType )
     {
         return idTypeConfigurationProvider.getIdTypeConfiguration( idType );
@@ -112,7 +127,7 @@ private IdTypeConfiguration getIdTypeConfiguration( IdType idType )
     public IdGenerator get( IdType idType )
     {
         IdGenerator generator = overriddenIdGenerators[idType.ordinal()];
-        return generator != null ? generator : super.get( idType );
+        return generator != null ? generator : delegate.get( idType );
     }
 
     public void maintenance()