code: @Override
      public void showErrors(final List<EditorError> errors) {
          StringBuilder sb = new StringBuilder();
          for (EditorError error : errors) {
  
              if (error.getEditor() == this) {
                  sb.append("\n").append(error.getMessage());
              }
          }
  
          boolean hasErrors = sb.length() > 0;
          if (!hasErrors) {
              view.clearError();
              return;
          }
  
          // Show the errors.
          view.showError(new SafeHtmlBuilder().appendEscaped(sb.substring(1)).toSafeHtml());
      }
docs: ***********************************************************
  * GWT EDITOR CONTRACT METHODS **
  ***********************************************************