code: public Object invokeOperation(String domain, String beanName, String operName, String... paramStrings)
  			throws Exception {
  		if (paramStrings.length == 0) {
  			return invokeOperation(ObjectNameUtil.makeObjectName(domain, beanName), operName, null, null);
  		} else {
  			return invokeOperation(ObjectNameUtil.makeObjectName(domain, beanName), operName, paramStrings);
  		}
  	}
docs: Invoke a JMX method with a domain/object-name as an array of parameter strings.
  
  @return The value returned by the method or null if none.