Invalid or insuficient scoping construct for @Nullable and @NonNull annotations

[elopezvalecky]

The @Nullable and @NonNull annotations does not meet all possible use of it as it is done in jrs305 or even the Jakarta EE

java: scoping construct cannot be annotated with type-use annotation: @org.checkerframework.checker.nullness.qual.Nullable
For a construct like

@Nullable
public Map.Entry<Object, Object> intersects() {
...
}

---

Comparing to other implementations of @Nullable for example, I found that in checker-qual, the annotation is defined as

...
@Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
...
public @interface Nullable {}

And this prevents the use of the annotations at any scope causing issues on migration when moving away from findbugs:jsr305

But looking at jakarta.annotations:jakarta.annotations-api:2.1.1 for example, the annotation is defined without @Target (source: https://github.com/jakartaee/common-annotations-api/blob/2.1.1/api/src/main/java/jakarta/annotation/Nullable.java) same as FindBugs one

Also, JetBrain defines this annotation, but for this particular one they make use of @Target but they do declare all possibles locations explicitly (source: https://github.com/JetBrains/java-annotations/blob/master/common/src/main/java/org/jetbrains/annotations/Nullable.java)

[mernst]

If you search for the error message in the Checker Framework manual, you will find https://checkerframework.org/manual/#common-problems-non-typechecking which explains that @Nullable Map.Entry is wrong since @Nullable refers to Entry, not to Map.
Other relevant sections are https://checkerframework.org/manual/#faq-declaration-annotations-moved and https://checkerframework.org/manual/#faq-type-annotation-formatting .

It is true that the @Nullable of the Checker Framework is not a drop-in replacement for every other @Nullable annotation (that would be impossible, since they differ). You need to:

• change your imports and
• fix wrong syntax in the few places it occurs.

The Checker Framework uses type annotations, which is the right approach for Java 8+ and which other toolsets (except abandoned ones like jsr305) are also coming to adopt.

[elopezvalecky]

Thanks so much for the reply, definitely there are some Java fundamental that I might have to revisit again. 😄