code: public static Object toRDF(Object input, JsonLdTripleCallback callback) throws JsonLdError {
          return toRDF(input, callback, new JsonLdOptions(""));
      }
docs: Outputs the RDF dataset found in the given JSON-LD object, using the
  default {@link JsonLdOptions}.
  
  @param input
  the JSON-LD input.
  @param callback
  A callback that is called when the input has been converted to
  Quads (null to use options.format instead).
  @return A JSON-LD object.
  @throws JsonLdError
  If there is an error converting the dataset to JSON-LD.