code: @Override
      public void updateFieldContent(String text) {
  
          if (!m_initialUpdateCalled) {
              m_initialUpdateCalled = true;
              if ("".equals(text)) {
                  valueChange(false);
                  Scheduler.get().scheduleFixedDelay(new RepeatingCommand() {
  
                      public boolean execute() {
  
                          if (isAttached()) {
                              valueChange(false);
                              return true;
                          } else {
                              return false;
                          }
                      }
                  }, 100);
                  return;
              }
  
          }
          super.updateFieldContent(text);
      }
docs: @see com.vaadin.client.ui.VTextField#updateFieldContent(java.lang.String)
  
  We have to override this method to prevent its value being overwritten by Vaadin and to make
  sure that the real value is sent to the server.