code: public FactorGraph addInferenceHint(InferenceHint newInferenceHint) {
      return new FactorGraph(variables, factors, factorNames, variableFactorMap, factorVariableMap,
          conditionedVariables, conditionedValues, newInferenceHint);
    }
docs: Gets a new {@code FactorGraph} identical to this one, with an
  added inference hint. {@code inferenceHint} is a suggestion for
  performing efficient inference with {@code this}.
  {@code inferenceHint} can be {@code null}, in which case the hint
  is ignored during inference.