Remove superfluous method definition

hashCode is defined in Object

src/net/java/sip/communicator/service/protocol/ProtocolProviderService.java

@@ -210,13 +210,6 @@ public void removeRegistrationStateChangeListener(
      */
     public void shutdown();
 
-    /**
-     * A hashcode allowing usage of protocol providers as keys in Hashtables.
-     * @return an int that may be used when storing protocol providers as
-     * hashtable keys.
-     */
-    public int hashCode();
-
     /**
      * Returns the AccountID that uniquely identifies the account represented by
      * this instance of the ProtocolProviderService.