docs: public boolean readOnlyRequest( final String requestId ) {
          if ( !_blacklist.containsKey( requestId ) ) {
              if ( _log.isDebugEnabled() ) {
                  _log.debug( "Registering readonly request: " + requestId );
              }
              incrementOrPut( _readOnlyRequests, requestId );
              return true;
          }
          return false;
      }