private void checkMethodReference(PsiMethodReferenceExpression expression, @NotNull ProblemsHolder holder) {
    PsiMethod superMethod = LambdaUtil.getFunctionalInterfaceMethod(expression);
    PsiMethod targetMethod = tryCast(expression.resolve(), PsiMethod.class);
    if (superMethod == null || targetMethod == null) return;

    PsiElement refName = expression.getReferenceNameElement();
    assert refName != null;
    if (isNullableOverridingNotNull(check(targetMethod, holder, expression.getType()), superMethod)) {
      reportProblem(holder, refName, "inspection.nullable.problems.Nullable.method.overrides.NotNull",
                    getPresentableAnnoName(targetMethod), getPresentableAnnoName(superMethod));
    }
  }
private void checkMethodReference(PsiMethodReferenceExpression expression, @NotNull ProblemsHolder holder)