code: @Nonnull
    public FineUploader5Chunking setParamNamePartIndex (@Nonnull @Nonempty final String sParamNamePartIndex)
    {
      ValueEnforcer.notEmpty (sParamNamePartIndex, "ParamNamePartIndex");
      m_sChunkingParamNamesPartIndex = sParamNamePartIndex;
      return this;
    }
docs: Name of the parameter passed with a chunked request that specifies the
  index of the associated partition.
  
  @param sParamNamePartIndex
  New value. May neither be <code>null</code> nor empty.
  @return this for chaining