Bug#1052473: libgoogle-gson-java: FTBFS with OpenJDK 21 due to new compiler warnings

[Emmanuel Bourg]

Package: libgoogle-gson-java
Version: 2.10-1
Severity: important
Tags: ftbfs sid trixie
User: debian-java at lists.debian.org
Usertags: default-java21


libgoogle-gson-java fails to build with OpenJDK 21, the code is compiled with
the -Werror flag and javac now emits new warnings, thus triggering an error:

  [INFO] -------------------------------------------------------------
  [WARNING] COMPILATION WARNING :
  [INFO] -------------------------------------------------------------
  [WARNING] /<<PKGBUILDDIR>>/gson/src/main/java/com/google/gson/stream/JsonReader.java:[1609,21] implicit cast from int to char in compound assignment is possibly lossy
  [WARNING] /<<PKGBUILDDIR>>/gson/src/main/java/com/google/gson/stream/JsonReader.java:[1611,21] implicit cast from int to char in compound assignment is possibly lossy
  [WARNING] /<<PKGBUILDDIR>>/gson/src/main/java/com/google/gson/stream/JsonReader.java:[1613,21] implicit cast from int to char in compound assignment is possibly lossy
  [WARNING] /<<PKGBUILDDIR>>/gson/src/main/java/com/google/gson/internal/$Gson$Types.java:[484,24] non-transient instance field of a serializable class declared with a non-serializable type
  [WARNING] /<<PKGBUILDDIR>>/gson/src/main/java/com/google/gson/internal/$Gson$Types.java:[485,24] non-transient instance field of a serializable class declared with a non-serializable type
  [WARNING] /<<PKGBUILDDIR>>/gson/src/main/java/com/google/gson/internal/$Gson$Types.java:[486,26] non-transient instance field of a serializable class declared with an array having a non-serializable base component type java.lang.reflect.Type
  [WARNING] /<<PKGBUILDDIR>>/gson/src/main/java/com/google/gson/internal/$Gson$Types.java:[553,24] non-transient instance field of a serializable class declared with a non-serializable type
  [WARNING] /<<PKGBUILDDIR>>/gson/src/main/java/com/google/gson/internal/$Gson$Types.java:[587,24] non-transient instance field of a serializable class declared with a non-serializable type
  [WARNING] /<<PKGBUILDDIR>>/gson/src/main/java/com/google/gson/internal/$Gson$Types.java:[588,24] non-transient instance field of a serializable class declared with a non-serializable type
  [INFO] 9 warnings
  [INFO] -------------------------------------------------------------
  [INFO] -------------------------------------------------------------
  [ERROR] COMPILATION ERROR :
  [INFO] -------------------------------------------------------------
  [ERROR] /<<PKGBUILDDIR>>/gson/src/main/java/com/google/gson/stream/JsonReader.java: warnings found and -Werror specified
  [INFO] 1 error
  [INFO] -------------------------------------------------------------