code: private void startAsyncValidation(final String formValidationHandler, final String config) {
  
          CmsRpcAction<Map<String, CmsValidationResult>> action = new CmsRpcAction<Map<String, CmsValidationResult>>() {
  
              /**
               * @see org.opencms.gwt.client.rpc.CmsRpcAction#execute()
               */
              @Override
              public void execute() {
  
                  final Map<String, String> values = new HashMap<String, String>();
                  for (I_CmsFormField field : m_fields) {
                      values.put(field.getId(), field.getModelValue());
                  }
                  start(0, false);
                  CmsCoreProvider.getService().validate(formValidationHandler, m_validationQueries, values, config, this);
              }
  
              /**
               * @see org.opencms.gwt.client.rpc.CmsRpcAction#onResponse(java.lang.Object)
               */
              @Override
              protected void onResponse(Map<String, CmsValidationResult> result) {
  
                  stop(false);
                  onReceiveValidationResults(result);
              }
  
          };
          action.execute();
      }
docs: Starts the asynchronous validation.<p>
  
  @param formValidationHandler the form validator class to use
  @param config the form validator configuration string