removed entities added for the pid graph dump

dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/dump/pidgraph/Entity.java

@@ -1,23 +0,0 @@
-
-package eu.dnetlib.dhp.schema.dump.pidgraph;
-
-import java.io.Serializable;
-
-public class Entity implements Serializable {
-	private String id;
-
-	public String getId() {
-		return id;
-	}
-
-	public void setId(String id) {
-		this.id = id;
-	}
-
-	public static Entity newInstance(String id) {
-		Entity entity = new Entity();
-		entity.id = id;
-
-		return entity;
-	}
-}