Unreported "illegal reference to static field from initializer" in relation to javac

Copied and updated from https://bugs.eclipse.org/bugs/show_bug.cgi?id=577373:

Originally I mentioned this in https://bugs.eclipse.org/bugs/show_bug.cgi?id=533475#c3, but it seems to be a different error since that bug was fixed and this one remains.

The code

```java
enum MyEnum {
;

private static MyEnum selected;

private MyEnum() {
Supplier s = () -> selected = this;
}
}
```

compiles fine in Eclipse, but using Gradle I get the error:

```
C:\ZSwitch\src\main\java\switchTests\SwitchTest.java:39: error: illegal reference to static field from initializer
Supplier s = () -> selected = this;
^
```
I don't know which compiler is correct, but unless the specifications are lenient, these should be aligned.

I first encountered it with Java 10 and Eclipse 4.7.3, and it's the same with Java 21 and Eclipse 4.29.