Play Framework

fix(jobs): a job run inline joins its caller's invocation

A job run with call() or run() from inside an action is on the
request's own thread. It opened a second invocation there, and when it
ended every plugin's teardown ran against the request's state:
JobsPlugin dropped the after-request queue, so the request ended with a
NullPointerException and a 500, and DBPlugin, JPAPlugin and
ValidationPlugin closed the connection, the EntityManager and the
validation errors the action was still using. The same happened to a
job that ran another job inline.

Job.call() now checks whether its thread already has an invocation
open. If so, only the job's own body runs, under a job id like any
other run: in the caller's transaction, with no plugin hook called a
second time, and a failure is thrown to the caller. A job on a thread
of its own (now(), in(), afterRequest(), the scheduler, synchronous
start and stop jobs) is unchanged.

Covered by InlineJobFunctionalTest against the real server with JPA;
without the fix it also leaves JpaLazyPoolTest a leaked connection.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KDUoh3KhBpfjXn4rV6H356