code: public void importRtfFragment(InputStream documentSource, RtfImportMappings mappings) throws IOException, DocumentException {
          importRtfFragment(documentSource, mappings, null);
      }
docs: Adds a fragment of an RTF document to the current RTF document being generated.
  Since this fragment doesn't contain font or color tables, all fonts and colors
  are mapped to the default font and color. If the font and color mappings are
  known, they can be specified via the mappings parameter.
  
  @param documentSource The InputStream to read the RTF fragment from.
  @param mappings The RtfImportMappings that contain font and color mappings to apply to the fragment.
  @throws IOException On errors reading the RTF fragment.
  @throws DocumentException On errors adding to this RTF fragment.
  @since 2.1.0