docs: add a code snippet for the sync api

[changsongd]

• Added a sync api code snippet

[snippet-bot]

Here is the summary of possible violations 😱

There is a possible violation for not having product prefix.

• samples/snippets/src/main/java/com/example/optimizationai/SyncApi.java:19, tag cloudoptimization_sync_api

The end of the violation section. All the stuff below is FYI purposes only.

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Here is the summary of changes.

You are about to add 1 region tag.

• samples/snippets/src/main/java/com/example/optimizationai/SyncApi.java:19, tag cloudoptimization_sync_api

You are about to delete 1 region tag.

• samples/snippets/pom.xml:29, tag optimizationai_install_with_bom

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[suztomo]

[INFO] --- maven-surefire-plugin:3.0.0-M5:test (default-test) @ -snapshot ---
[INFO]
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.example.optimizationai.SyncApiTest
[ERROR] Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.119 s <<< FAILURE! - in com.example.optimizationai.SyncApiTest
[ERROR] com.example.optimizationai.SyncApiTest.testSyncApi  Time elapsed: 0.027 s  <<< ERROR!
java.io.FileNotFoundException: resources/sync_request.textproto (No such file or directory)
	at java.io.FileInputStream.open0(Native Method)
	at java.io.FileInputStream.open(FileInputStream.java:195)
	at java.io.FileInputStream.<init>(FileInputStream.java:138)
	at java.io.FileInputStream.<init>(FileInputStream.java:93)
	at com.example.optimizationai.SyncApi.callSyncApi(SyncApi.java:48)
	at com.example.optimizationai.SyncApiTest.testSyncApi(SyncApiTest.java:57)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)