code: @Nonnull
    public ICommonsList <String> getHeaders (@Nullable final String sName)
    {
      return new CommonsArrayList <> (m_aHeaders.get (_unifyHeaderName (sName)));
    }
docs: Return all values for the given header as a List of value objects.
  
  @param sName
  the name of the header
  @return the associated header values, or an empty List if none