diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/dbinitialization/DatabaseEnvironment.java b/src/main/java/org/gcube/informationsystem/resourceregistry/dbinitialization/DatabaseEnvironment.java
index 3b330f3..7c5558c 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/dbinitialization/DatabaseEnvironment.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/dbinitialization/DatabaseEnvironment.java
@@ -136,6 +136,9 @@ public class DatabaseEnvironment {
 	
 	private static final Key KEY;
 	
+	public static final String V = "V";
+	public static final String E = "E";
+	
 	static {
 		Properties properties = new Properties();
 		InputStream input = null;
@@ -381,10 +384,10 @@ public class DatabaseEnvironment {
 				OSchema oSchema = oMetadata.getSchema();
 				OClass oRestricted = oSchema.getClass(OSecurity.RESTRICTED_CLASSNAME);
 				
-				OClass v = oSchema.getClass("V");
+				OClass v = oSchema.getClass(V);
 				v.addSuperClass(oRestricted);
 				
-				OClass e = oSchema.getClass("E");
+				OClass e = oSchema.getClass(E);
 				e.addSuperClass(oRestricted);
 				
 				oDatabaseSession.commit();
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/utils/HeaderUtility.java b/src/main/java/org/gcube/informationsystem/resourceregistry/utils/HeaderUtility.java
index dac4ae7..d907fe9 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/utils/HeaderUtility.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/utils/HeaderUtility.java
@@ -21,7 +21,6 @@ import org.slf4j.LoggerFactory;
 
 import com.orientechnologies.orient.core.record.OElement;
 import com.orientechnologies.orient.core.record.impl.ODocument;
-import com.tinkerpop.blueprints.Edge;
 
 /**
  * @author Luca Frosini (ISTI - CNR)
@@ -121,11 +120,13 @@ public class HeaderUtility {
 		return header;
 	}
 	
+	/*
 	public static Header addHeader(Edge edge, UUID uuid) {
 		Header header = createHeader(uuid);
 		edge.setProperty(IdentifiableElement.HEADER_PROPERTY, header);
 		return header;
 	}
+	*/
 	
 	public static Header getHeader(OElement element) throws ResourceRegistryException {
 		return Utility.getPropertyDocument(Header.class, element, IdentifiableElement.HEADER_PROPERTY);