code: public Object invoke(ObjectName objectName,String operationName,Object[]  params, String[] signature)
     {
  	   return invoke(null, objectName, operationName,params, signature);
     }
docs: >p>Invokes an operation on an MBean.</p>
  @param objectName
  @param operationName
  @param params
  @param signature
  @return the return object from the method call