diff --git a/src/main/java/eu/dnetlib/dhp/schema/common/EntityType.java b/src/main/java/eu/dnetlib/dhp/schema/common/EntityType.java
index 13ef3b9..a7628a5 100644
--- a/src/main/java/eu/dnetlib/dhp/schema/common/EntityType.java
+++ b/src/main/java/eu/dnetlib/dhp/schema/common/EntityType.java
@@ -1,8 +1,6 @@
 
 package eu.dnetlib.dhp.schema.common;
 
-import eu.dnetlib.dhp.schema.oaf.OafEntity;
-
 /** Actual entity types in the Graph */
 public enum EntityType {
 	publication, dataset, otherresearchproduct, software, datasource, organization, project, person;
@@ -14,7 +12,7 @@ public enum EntityType {
 	 * @param <T> actual OafEntity subclass
 	 * @return the EntityType associated to the given class
 	 */
-	public static <T extends Object> EntityType fromClass(Class<T> clazz) {
+	public static <T> EntityType fromClass(Class<T> clazz) {
 
 		return EntityType.valueOf(clazz.getSimpleName().toLowerCase());
 	}
diff --git a/src/main/java/eu/dnetlib/dhp/schema/common/ModelSupport.java b/src/main/java/eu/dnetlib/dhp/schema/common/ModelSupport.java
index e5c2959..e00ef19 100644
--- a/src/main/java/eu/dnetlib/dhp/schema/common/ModelSupport.java
+++ b/src/main/java/eu/dnetlib/dhp/schema/common/ModelSupport.java
@@ -212,7 +212,7 @@ public class ModelSupport {
 	private ModelSupport() {
 	}
 
-	public static <E extends Object> String getIdPrefix(Class<E> clazz) {
+	public static <E> String getIdPrefix(Class<E> clazz) {
 		return idPrefixMap.get(clazz);
 	}