…cp OTel metrics (#4329)

* feat: Add ClientContext to Options and propagate to RPCs

This change adds support for ClientContext in Options and ensures it is
propagated to ExecuteSql, Read, Commit, and BeginTransaction requests.
It aligns with go/spanner-client-scoped-session-state design.

- Added RequestOptions.ClientContext to Options.
- Refactored request option building to Options.toRequestOptionsProto.
- Updated AbstractReadContext, TransactionRunnerImpl, and SessionImpl to use the shared logic.
- Added tests.

* feat: Add ClientContext support to Connection API

This change adds support for setting and propagating ClientContext in the
Spanner Connection API. ClientContext allows propagating client-scoped
session state (e.g., secure parameters) to Spanner RPCs.

- Added setClientContext/getClientContext to Connection interface and implementation.
- Implemented state propagation from Connection to UnitOfWork and its implementations (ReadWriteTransaction, SingleUseTransaction).
- Fixed accidental import removal in OptionsTest.java.
- Fixed TransactionRunnerImplTest to correctly verify ClientContext propagation.
- Added ClientContextMockServerTest for end-to-end verification.

* Address code-review comments

…#4319)

* chore: Update generation configuration at Thu Jan 29 02:52:51 UTC 2026

* chore: Update generation configuration at Fri Jan 30 02:53:36 UTC 2026

* chore: Update generation configuration at Sat Jan 31 02:50:11 UTC 2026

* chore: generate libraries at Sat Jan 31 02:50:43 UTC 2026

* chore: Update generation configuration at Sun Feb  1 02:59:38 UTC 2026

* chore: Update generation configuration at Tue Feb  3 02:56:52 UTC 2026

* chore: Update generation configuration at Wed Feb  4 02:54:27 UTC 2026

* chore: Update generation configuration at Thu Feb  5 02:55:51 UTC 2026

* chore: generate libraries at Thu Feb  5 02:56:33 UTC 2026

Synchronize the start() and stop() methods of the session maintainer to prevent
them from running at the same time. That could cause a data race on the scheduled
future that the start() method sets, and the stop() method reads.

…v3.56.1 (#4331)

* chore: handle unary gRPC call ordering in KeyAwareChannel

* incorporate suggestions

* test: add tests for location API

* fix test

* add more tests

* add test for executesSql update cache

---------

Co-authored-by: Knut Olav Løite <koloite@gmail.com>

🤖 I have created a release *beep* *boop*
---


### Updating meta-information for bleeding-edge SNAPSHOT release.

---
This PR was generated with [Release Please](https://togithub.com/googleapis/release-please). See [documentation](https://togithub.com/googleapis/release-please#release-please).

* feat: Add gRPC A66/A94 metrics.

This change adds the `grpc.client.attempt.started` metric in
the
[A66](https://github.com/grpc/proposal/blob/master/A66-otel-stats.md)
proposal and all the subchannel metrics in the
[A94](https://github.com/grpc/proposal/blob/master/A94-subchannel-otel-metrics.md)
proposal. Metric-specific attributes were also added.

The change also updates the metric exporter to use the same timestamp
for start and end time for GAUGE type data point. This is required by
the StackDriver or otherwise the export will fail.

* Enable different attributes in different gRPC metrics

* Enable optional labels

---------

Co-authored-by: rahul2393 <irahul@google.com>

…4340)

* chore: route multi-use read-only txn reads via location-aware cache

* incorporate changes

* chore(main): release 6.110.0

* chore: generate libraries at Wed Feb 11 03:24:17 UTC 2026

---------

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>
Co-authored-by: cloud-java-bot <cloud-java-bot@google.com>
Co-authored-by: rahul2393 <irahul@google.com>