void addCustomNullabilityProblem(@NotNull PsiExpression expression, @NotNull NullabilityProblemKind<? super PsiExpression> problem) {
    myCustomNullabilityProblems.put(expression, problem);
  }
void addCustomNullabilityProblem(@NotNull PsiExpression expression, @NotNull NullabilityProblemKind<? super PsiExpression> problem)