code: public void addListenScope( Object scopeKey )
      {
          assert scopeKey != null;
  
          if ( _listenScopes == null )
          {
              _listenScopes = new ArrayList();
          }
  
          _listenScopes.add( scopeKey );
      }
docs: Adds a scope to "listen" to.  This scope will see all request parameters from a ScopedRequest
  of the given scope.