Build fails under JDK 23 and JDK 24

I'm testing with a command like the one shown here:

https://github.com/google/auto/pull/1899#issuecomment-2741125656

If I point `JAVA_HOME` to JDK 23 or JDK 24 (or if I point it to nothing, since JDK 24 is now the default on my machine), I get an error. If I set it to JDK 22 (or JDK 17 or presumably most other versions), everything is fine.

There error is unilluminating, at least to me based on what Maven gives me (and `-X -e` doesn't seem to help):

```
[INFO] --- compiler:3.14.0:testCompile (default-testCompile) @ gwtserializer ---
[INFO] Recompiling the module because of changed source code.
[INFO] Compiling 2 source files with javac [debug deprecation target 1.8] to target/test-classes
[INFO] -------------------------------------------------------------
[WARNING] COMPILATION WARNING : 
[INFO] -------------------------------------------------------------
[WARNING] bootstrap class path is not set in conjunction with -source 8
  not setting the bootstrap class path may lead to class files that cannot run on JDK 8
    --release 8 is recommended instead of -source 8 -target 1.8 because it sets the bootstrap class path automatically
[WARNING] source value 8 is obsolete and will be removed in a future release
[WARNING] target value 8 is obsolete and will be removed in a future release
[WARNING] To suppress warnings about obsolete options, use -Xlint:-options.
[INFO] 4 warnings 
[INFO] -------------------------------------------------------------
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] /tmp/tmp.779ZkLaA1e/auto/value/src/it/gwtserializer/src/test/java/com/google/auto/value/client/GwtSerializerTest.java:[126,18] cannot find symbol
  symbol:   class AutoValue_GwtSerializerTest_Simple
  location: class com.google.auto.value.client.GwtSerializerTest.Simple
[ERROR] /tmp/tmp.779ZkLaA1e/auto/value/src/it/gwtserializer/src/test/java/com/google/auto/value/client/GwtSerializerTest.java:[136,63] package AutoValue_GwtSerializerTest_SimpleWithBuilder does not exist
[ERROR] /tmp/tmp.779ZkLaA1e/auto/value/src/it/gwtserializer/src/test/java/com/google/auto/value/client/GwtSerializerTest.java:[155,18] cannot find symbol
  symbol:   class AutoValue_GwtSerializerTest_Nested
  location: class com.google.auto.value.client.GwtSerializerTest.Nested
[ERROR] /tmp/tmp.779ZkLaA1e/auto/value/src/it/gwtserializer/src/test/java/com/google/auto/value/client/GwtSerializerTest.java:[167,63] package AutoValue_GwtSerializerTest_NestedWithBuilder does not exist
[ERROR] /tmp/tmp.779ZkLaA1e/auto/value/src/it/gwtserializer/src/test/java/com/google/auto/value/client/GwtSerializerTest.java:[186,18] cannot find symbol
  symbol:   class AutoValue_GwtSerializerTest_Generics
  location: class com.google.auto.value.client.GwtSerializerTest.Generics<T>
[ERROR] /tmp/tmp.779ZkLaA1e/auto/value/src/it/gwtserializer/src/test/java/com/google/auto/value/client/GwtSerializerTest.java:[196,65] package AutoValue_GwtSerializerTest_GenericsWithBuilder does not exist
[INFO] 6 errors 
```

[]