code: @Nonnull
    @Nonempty
    public String getAsString ()
    {
      return CCSSValue.PREFIX_RGBA_OPEN +
             m_sRed +
             ',' +
             m_sGreen +
             ',' +
             m_sBlue +
             ',' +
             m_sOpacity +
             CCSSValue.SUFFIX_RGBA_CLOSE;
    }
docs: {@inheritDoc}
  
  @since 3.8.3