Parse Java annotations on array dimensions (Scala 3 backport)

[mkurz]

Backport the Scala 3 Java parser fix for annotations that appear before array brackets, such as String @Nullable [] and nested annotated arrays.

Scala 3 fixed the same parser gap in scala/scala3#22391. This applies the corresponding optArrayBrackets change to the Scala 2 Java parser and extends the existing Java type annotation positive test.

Scala 3 related issues/PRs/commits:

• Cannot parse Java file with type annotations on array or path selection scala3#19642
• Fix annotations being not expected in the middle of an array type by java parser scala3#22391
• commit: scala/scala3@9c971be
• backport commit for Scala 3.3.x: scala/scala3@75450da

---

To reproduce:

J.java

public interface J {
  String @Nullable [] values();
}

Nullable.java

import java.lang.annotation.ElementType;
import java.lang.annotation.Target;

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

Compiling with Java 8 works and produces class files:

$ java -version
openjdk version "1.8.0_492"
OpenJDK Runtime Environment (Temurin)(build 1.8.0_492-b09)
OpenJDK 64-Bit Server VM (Temurin)(build 25.492-b09, mixed mode)

$ javac Nullable.java J.java
$ ls -1 *.class
J.class
Nullable.class

The Scala 3.3 compiler accepts the files (does not create the class files however which I guess is expected):

$ scala -version
Scala code runner version 3.3.7 -- Copyright 2002-2025, LAMP/EPFL

$ scalac -usejavacp Nullable.java J.java
$ echo $?
0

Scala 2.13 fails:

$ scala -version
Scala code runner version 2.13.18 -- Copyright 2002-2025, LAMP/EPFL and Lightbend, Inc. dba Akka

$ scalac -usejavacp Nullable.java J.java
J.java:2: error: identifier expected but `@` found.
  String @Nullable [] values();
         ^
1 error

[mkurz]

I amended the commit with one more test case for Java type-use annotations before varargs:

void varargs(String @NotNull ... values) {}

This mirrors the Scala 3 test added in

• Test Java annotations on varargs element types scala3#26188

This PR is ready now.