code: public CmsResourceFilter addRequireFlags(int flags) {
  
          CmsResourceFilter extendedFilter = (CmsResourceFilter)clone();
  
          extendedFilter.m_flags = flags;
          extendedFilter.m_filterFlags = REQUIRED;
          extendedFilter.updateCacheId();
  
          return extendedFilter;
      }
docs: Returns an extended filter to guarantee a distinct resource flags of the filtered resources.<p>
  
  @param flags the required resource flags
  @return a filter requiring the given resource flags