`java_single_jar` exposes `exclude_pattern` and forwards `--exclude_pattern`, but Bazel OSS `singlejar` doesn’t accept it

[bc-lee]

Problem

The exclude_pattern attribute in java_single_jar is forwarded to singlejar as --exclude_pattern. However, the open-source Bazel singlejar implementation does not define that option (e.g. src/tools/singlejar/options.cc).
As a result, exclusion-by-pattern is currently unusable (or fails with an “unknown option” error) in OSS toolchains, e.g.: singlejar_local: Bad command line argument --exclude_pattern.

Proposal

Short term: Deprecate/hide exclude_pattern in OSS rules_java to avoid confusion and build failures.

Long term: Align rules_java and OSS Bazel singlejar by implementing a supported pattern-based exclusion mechanism in OSS singlejar and exposing it cleanly in java_single_jar (preferably globs via a new attribute like exclude_globs).
Use case: excluding specific packages/classes/resources when building a “single jar” because they are provided by the runtime/platform (Android, app servers, shaded runtime libs), to avoid conflicts and reduce output size.

[katre]

Pinging @asmundak and @bazelbuild/java-team