Play Framework

build: stop javadoc fetching link targets over the network

`ant package` intermittently emitted:

  [javadoc] error: Error fetching URL: https://docs.hibernate.org/orm/4.2/javadocs/
  (java.io.IOException: Server returned HTTP response code: 525 ...)

Three <link> entries had offline="false", which makes javadoc fetch the remote
element-list at build time. The build therefore succeeded or failed on a third
party's uptime, with nothing in the repo having changed — 525 is a Cloudflare
edge failure. The same thing had already happened once, to the javadoc.io link,
and was fixed there with a vendored list; the other three were left online.

All remaining links are now offline="true" with a local element-list. The href
stays live so links in the generated docs still resolve for readers; only the
build-time fetch is gone. There is no offline="false" left, so `ant javadoc` no
longer touches the network at all.

Two of the three were also simply wrong:

  - Oracle JDK was pinned to 21 while build-release=25. Now 25, and the 587
    files carrying JDK cross-links point at the right API.
  - Hibernate was pinned to 4.2 while the fork ships 7.4.5.Final — stale by
    three majors and about a decade.

The Hibernate link is dropped rather than repointed. It produced zero
cross-links in the generated docs at 4.2 and still zero when I tried it at 7.4,
because no play.* signature exposes a Hibernate type. That is why the staleness
went unnoticed for so long: the link never emitted anything. Vendoring an 8KB
element-list that must be refreshed on every Hibernate bump, to produce nothing,
is worse than not having the link.

The c3p0 link is dropped outright: c3p0 is not in dependencies.yml, has no jar
in lib/, and is not imported anywhere — only mentioned in a HikariCP comment
about config back-compat.

ant package and ant test both pass; javadoc emits no diagnostics.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>