diff --git a/src/main/java/org/gcube/informationsystem/types/reference/entities/EntityType.java b/src/main/java/org/gcube/informationsystem/types/reference/entities/EntityType.java
index 48f9a42..6a64b44 100644
--- a/src/main/java/org/gcube/informationsystem/types/reference/entities/EntityType.java
+++ b/src/main/java/org/gcube/informationsystem/types/reference/entities/EntityType.java
@@ -1,14 +1,10 @@
 package org.gcube.informationsystem.types.reference.entities;
 
 import java.util.Set;
-import java.util.UUID;
 
-import org.gcube.com.fasterxml.jackson.annotation.JsonGetter;
 import org.gcube.com.fasterxml.jackson.annotation.JsonIgnoreProperties;
-import org.gcube.com.fasterxml.jackson.annotation.JsonSetter;
 import org.gcube.com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import org.gcube.informationsystem.base.reference.entities.EntityElement;
-import org.gcube.informationsystem.model.reference.properties.Metadata;
 import org.gcube.informationsystem.types.annotations.ISProperty;
 import org.gcube.informationsystem.types.impl.entities.EntityTypeImpl;
 import org.gcube.informationsystem.types.reference.Change;
@@ -29,24 +25,6 @@ public interface EntityType extends Type, EntityElement {
 
 	/* Type is just a Java useful class. The type is not created in the IS. Hence the fields must be redefined */
 	
-	@JsonGetter(value = UUID_PROPERTY)
-	@ISProperty(name = UUID_PROPERTY, description = "This UUID is be used to identify the instance univocally.", readonly = true, mandatory = true, nullable = false)
-	@Override
-	public UUID getUUID();
-
-	@JsonSetter(value = UUID_PROPERTY)
-	@Override
-	public void setUUID(UUID uuid);
-	
-	@JsonGetter(value = METADATA_PROPERTY)
-	@ISProperty(name=METADATA_PROPERTY, mandatory=true, nullable=false, description="Metadata associated with the instance that is automatically created/updated by the system.")
-	@Override
-	public Metadata getMetadata();
-	
-	@JsonSetter(value = METADATA_PROPERTY)
-	@Override
-	public void setMetadata(Metadata metadata);
-	
 	@Override
 	@ISProperty(name = Type.NAME_PROPERTY, readonly = true, mandatory = true, nullable = false)
 	public String getName();
diff --git a/src/main/java/org/gcube/informationsystem/types/reference/properties/PropertyType.java b/src/main/java/org/gcube/informationsystem/types/reference/properties/PropertyType.java
index be6b023..0ba53d3 100644
--- a/src/main/java/org/gcube/informationsystem/types/reference/properties/PropertyType.java
+++ b/src/main/java/org/gcube/informationsystem/types/reference/properties/PropertyType.java
@@ -29,8 +29,6 @@ public interface PropertyType<P extends PropertyElement> extends PropertyElement
 	
 	public static final String NAME = "PropertyType"; // PropertyType.class.getSimpleName();
 	
-	/* Type is just a Java useful class. The type is not created in the IS. Hence the fields must be redefined */
-	
 	@JsonGetter(value = UUID_PROPERTY)
 	@ISProperty(name = UUID_PROPERTY, description = "This UUID is be used to identify the instance univocally.", readonly = true, mandatory = true, nullable = false)
 	@Override
@@ -49,6 +47,8 @@ public interface PropertyType<P extends PropertyElement> extends PropertyElement
 	@Override
 	public void setMetadata(Metadata metadata);
 	
+	/* Type is just a Java useful class. The type is not created in the IS. Hence the fields must be redefined */
+	
 	@Override
 	@ISProperty(name = Type.NAME_PROPERTY, readonly = true, mandatory = true, nullable = false)
 	public String getName();
diff --git a/src/main/java/org/gcube/informationsystem/types/reference/relations/RelationType.java b/src/main/java/org/gcube/informationsystem/types/reference/relations/RelationType.java
index 9b3cb14..e34327a 100644
--- a/src/main/java/org/gcube/informationsystem/types/reference/relations/RelationType.java
+++ b/src/main/java/org/gcube/informationsystem/types/reference/relations/RelationType.java
@@ -1,14 +1,10 @@
 package org.gcube.informationsystem.types.reference.relations;
 
 import java.util.Set;
-import java.util.UUID;
 
-import org.gcube.com.fasterxml.jackson.annotation.JsonGetter;
 import org.gcube.com.fasterxml.jackson.annotation.JsonIgnoreProperties;
-import org.gcube.com.fasterxml.jackson.annotation.JsonSetter;
 import org.gcube.com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import org.gcube.informationsystem.base.reference.relations.RelationElement;
-import org.gcube.informationsystem.model.reference.properties.Metadata;
 import org.gcube.informationsystem.types.annotations.ISProperty;
 import org.gcube.informationsystem.types.impl.relations.RelationTypeImpl;
 import org.gcube.informationsystem.types.reference.Change;
@@ -32,24 +28,6 @@ public interface RelationType<S extends EntityType, T extends EntityType>
 	
 	/* Type is just a Java useful class. The type is not created in the IS. Hence the fields must be redefined */
 	
-	@JsonGetter(value = UUID_PROPERTY)
-	@ISProperty(name = UUID_PROPERTY, description = "This UUID is be used to identify the instance univocally.", readonly = true, mandatory = true, nullable = false)
-	@Override
-	public UUID getUUID();
-
-	@JsonSetter(value = UUID_PROPERTY)
-	@Override
-	public void setUUID(UUID uuid);
-	
-	@JsonGetter(value = METADATA_PROPERTY)
-	@ISProperty(name=METADATA_PROPERTY, mandatory=true, nullable=false, description="Metadata associated with the instance that is automatically created/updated by the system.")
-	@Override
-	public Metadata getMetadata();
-	
-	@JsonSetter(value = METADATA_PROPERTY)
-	@Override
-	public void setMetadata(Metadata metadata);
-	
 	@Override
 	@ISProperty(name = Type.NAME_PROPERTY, readonly = true, mandatory = true, nullable = false)
 	public String getName();