Do not close an externally-supplied MongoClient in GORM for MongoDB

[codeconsole]

What

GORM's connection-source shutdown closes any Closeable source, and com.mongodb.client.MongoClient is Closeable, so a client handed to GORM — a Spring-managed bean, or one passed to new MongoDatastore(mongoClient, ...) — was closed when the datastore shut down. That double-closes a client whose lifecycle is owned elsewhere.

This makes GORM not close a MongoClient it did not create:

• DefaultConnectionSource gains a non-closeable mode (new 4-arg constructor + isCloseable()); the existing constructor is unchanged, so there is no behavior change for current callers.
• MongoDatastore.createDefaultConnectionSources wraps an externally-supplied client as non-closeable.
• MongoDbGormAutoConfiguration implements DisposableBean and closes only the client it created itself; a client supplied as a bean is left for the application context to close.

GORM still closes clients it creates from grails.mongodb.* configuration.

Why

• Removes a redundant double-close in the common Spring Boot setup (Spring already owns and closes the MongoClient bean).
• Establishes "whoever creates the client owns closing it" — the safe basis for sharing one MongoClient across GORM and other consumers.

Behavior change

The only externally-visible change: callers that relied on MongoDatastore.close() to also close a client they passed in must now close it themselves. Documented in the upgrade notes.

Tests

• DefaultConnectionSourceSpec — closes by default; no-op when non-closeable; closes an AutoCloseable when closeable.
• MongoDatastoreExternalClientSpec — a supplied client is not closed on datastore shutdown.
• MongoDbGormAutoConfigurationCloseSpec — the auto-config closes only an internally-created client.

Targets 8.0.x.

[jdaugherty]

Why are you using gorm's mongo and spring's mongo?

[codeconsole]

This PR doesn't introduce any GORM↔Spring Mongo mixing — MongoDbGormAutoConfiguration has reused Spring Boot's auto-configured MongoClient (from MongoAutoConfiguration/MongoProperties) since 1.0, to avoid opening a second connection in a Boot app. The only change here is lifecycle: GORM no longer closes a MongoClient it didn't create (e.g. the Spring-managed bean), and the auto-config closes only the client it created itself. The Spring-mongo references in the diff are pre-existing context around the new destroy() method. (Note this is Spring Boot's Mongo auto-config, not Spring Data MongoDB.)

[borinquenkid]

I'm sure this is not a totally rational fear, but I would point to #15678 since there was reworking of datastore creation

[testlens-app]

✅ All tests passed ✅

🏷️ Commit: d95eb44
▶️ Tests: 30243 executed
⚪️ Checks: 44/44 completed

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[codeconsole]

I went through #15678's current diff (100 files): it's entirely in grails-data-hibernate5/grails-data-hibernate7 (plus graphql and gradle), and the datastore-creation rework there is on the Hibernate datastores. It doesn't touch DefaultConnectionSource or anything else in grails-datastore-core, nor MongoDatastore — the files this PR changes — so there's no file overlap and this rebases cleanly when #15678 lands. The change here is also additive (a new DefaultConnectionSource constructor; the existing one is unchanged), so it doesn't alter the creation path for stores that don't opt in.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.0000%. Comparing base (098660a) to head (d95eb44).
⚠️ Report is 203 commits behind head on 8.0.x.

Additional details and impacted files

@@                Coverage Diff                @@
##                8.0.x   #15743         +/-   ##
=================================================
- Coverage     48.3729%        0   -48.3729%     
=================================================
  Files            1870        0       -1870     
  Lines           85457        0      -85457     
  Branches        14900        0      -14900     
=================================================
- Hits            41338        0      -41338     
+ Misses          37784        0      -37784     
+ Partials         6335        0       -6335     

see 1870 files with indirect coverage changes

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