refactor: adopt jspecify

[tenax66]

This is a pull request for issue #5320 .

• add the dependency for jspecify.
• applied the @Nullable annotation to several packages as a first step:spoon, spoon.compiler, spoon.metamodel and spoon.pattern.internal.

Note: This pull request does not include checks for annotations. We may use jspecify-reference-checker in the future.

[tenax66]

When annotating a return type of a method by jspecify's @Nullable, it should look like this.

public @Nullable String foo() {
  return ""
}

That is to say, the annotation is applied directly to the return type.

But annotations in that position don't pass Qodana's checks (MissortedModifiers).

[SirYwell]

When annotating a return type of a method by jspecify's @Nullable, it should look like this.

public @Nullable String foo() {
  return ""
}

That is to say, the annotation is applied directly to the return type.

But annotations in that position don't pass Qodana's checks (MissortedModifiers).

This is configurable in IntelliJ, but I don't know if/how it can be configured using the qodana.yaml. @MartinWitt maybe you know more about that?

[MartinWitt]

Hey, The current Qodana config does not allow this directly, but you could try adding the `.idea` config file to the repo after changing the setting in IJ. If this does not work, disabling the rule with a comment why is also fine for me. Otherwise, great progress.

[tenax66]

you could try adding the .idea config file to the repo after changing the setting in IJ.
If this does not work, disabling the rule with a comment why is also fine for me.

I tried the latter, as I could not find any information that the .idea folder can modify qodana's CI settings.

[MartinWitt]

@SirYwell can you provide the config file with the changed IJ setting?

[I-Al-Istannen]

Okay, I give up. It seems to work locally, but what do I know. Let's disable that modifier check.

[MartinWitt]

@I-Al-Istannen so we merge and fix this at a later stage?

[MartinWitt]

Thanks @tenax66 for your work.