private void collectVarsToResolve(Set<? super InferenceVariable> varsToResolve, InputOutputConstraintFormula formula) {
    final Set<InferenceVariable> inputVariables = formula.getInputVariables(this);
    if (inputVariables != null) {
      for (InferenceVariable inputVariable : inputVariables) {
        varsToResolve.addAll(inputVariable.getDependencies(this));
      }
      varsToResolve.addAll(inputVariables);
    }
  }
private void collectVarsToResolve(Set<? super InferenceVariable> varsToResolve, InputOutputConstraintFormula formula)