@Nullable
  private static String computeConstantReturnValue(PsiClass psiClass,
                                                   String methodName) {
    final UExpression expression = getReturnExpression(psiClass, methodName);
    if (expression == null) return null;

    return UastUtils.evaluateString(expression);
  }
@Nullable
  private static String computeConstantReturnValue(PsiClass psiClass,
                                                   String methodName)