Annotation not found in provided JUnit5 stub file

Working with checker-framework 3.48.4.
When configuring checker framework ti use provided JUnit5 stub (junit-assertions.astub), I have the following warning:
junit-assertions.astub:(line 56,col 2): Unknown annotation @EnsuresNonNull("#1").
Aside this warning, because the @EnsuresNonNull("#1") on assertNonNull is "not known", assertNonNull are not considered as ensuring non-nullness and my tests are not compiling.

I tried to copy the file in my project's resource folder, and specifying this folder in annotation processor -Astubs argument, and added the following missing import: import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
...but I get the same waning.

The warning is triggered by line 56 though my modified stub has the @EnsuresNonNull("#1") on line 57 because of the newly inserted import.

Thus :

• I failed to override JUnit5 stub location, annotation processor is obviously working with embedded junit-assertions.astub instead of mine
• an import is missing in JUnit5 stub; we sould insert import org.checkerframework.checker.nullness.qual.EnsuresNonNull; at line 13.

Start by locating the embedded junit-assertions.astub and reviewing how the annotation processor resolves the -Astubs option. Check the missing EnsuresNonNull import and the distinction between the embedded and project-provided stub, then verify that JUnit5 assertNonNull is recognized without the warning and provides the expected nullness information.