code: @Nullable
    private ICommonsOrderedMap <String, RequestParamMapItem> _getChildMapExceptLast (@Nonnull @Nonempty final String... aPath)
    {
      ValueEnforcer.notEmpty (aPath, "Path");
  
      ICommonsOrderedMap <String, RequestParamMapItem> aMap = m_aMap;
      // Until the second last object
      for (int i = 0; i < aPath.length - 1; ++i)
      {
        aMap = _getChildMap (aMap, aPath[i]);
        if (aMap == null)
          return null;
      }
      return aMap;
    }
docs: Iterate the root map down to the map specified by the passed path except
  for the last element.
  
  @param aPath
  The path to iterate. May neither be <code>null</code> nor empty.
  @return The map. May be <code>null</code> if the path did not find such a
  child.