docs: @Nonnull
    @ReturnsMutableCopy
    public ICommonsList <String> cancelUploadedFiles (@Nullable final String... aFieldNames)
    {
      final ICommonsList <String> ret = new CommonsArrayList <> ();
      if (ArrayHelper.isNotEmpty (aFieldNames))
      {
        m_aRWLock.writeLocked ( () -> {
          for (final String sFieldName : aFieldNames)
          {
            final TemporaryUserDataObject aUDO = m_aMap.remove (sFieldName);
            if (aUDO != null)
            {
              _deleteUDO (aUDO);
              ret.add (sFieldName);
            }
          }
        });
      }
      return ret;
    }