Code inspection: Declaration nullability inferred (type member is inferred to be not null)

This inspection reports a method, property, indexer, or operator whose return value is inferred to be never null. The inspection looks at the member body and suggests adding [NotNull] when the code always returns a non-null reference. For async and iterator members, it can suggest item-level annotations such as [ItemNotNull].

Example

In this case, the method always returns a non-null string. The quick-fix suggests annotating the method with the [NotNull] attribute.

                public class Settings
                {
                    public string GetName()
                    {
                        return "Default";
                    }
                }
            

                using JetBrains.Annotations;

                public class Settings
                {
                    [NotNull]
                    public string GetName()
                    {
                        return "Default";
                    }
                }
            

Quick-fix

Annotate the member with the inferred nullability attribute, usually [NotNull]. For iterators and async methods returning container-like values, the quick-fix can use [ItemNotNull].

28 March 2026