```
@Documented
@Retention(SOURCE)
@Target({})
@InvisibleQualifier
@SubtypeOf({})
public @interface Unqualified
```
A special annotation intended solely for representing an unqualified type in the qualifier hierarchy, as an argument to SubtypeOf.value(), in a type qualifier declaration.
This annotation may not be written in source code; it is an implementation detail of the checker.
Use this qualifier only when experimenting with very simple type systems. For any more realistic type systems, introduce a top and bottom qualifier that gets stored in bytecode.

See the Checker Framework Manual:
Subtyping Checker

Annotation Type Unqualified