code: public void registerEntity(CmsEntity entity) {
  
          if (m_validationContext == null) {
              m_validationContext = new CmsValidationContext();
          }
          if (m_handlerRegistration != null) {
              m_handlerRegistration.removeHandler();
          }
          m_paused = false;
          m_handlerRegistration = entity.addValueChangeHandler(this);
      }
docs: Registers the validation handler for the given entity.<p>
  
  @param entity the entity