docs(samples): added samples and tests for BigQuery export RPCs

[Sita04]

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

If you write sample code, please follow the samples format.

[generated-files-bot]

Warning: This pull request is touching the following templated files:

• .kokoro/presubmit/samples.cfg
• samples/snapshot/pom.xml
• samples/snippets/pom.xml

[snippet-bot]

Here is the summary of changes.

You are about to add 5 region tags.

• samples/snippets/src/main/java/com/google/cloud/examples/securitycenter/snippets/bigqueryexport/CreateBigQueryExport.java:19, tag securitycenter_create_bigquery_export
• samples/snippets/src/main/java/com/google/cloud/examples/securitycenter/snippets/bigqueryexport/DeleteBigQueryExport.java:19, tag securitycenter_delete_bigquery_export
• samples/snippets/src/main/java/com/google/cloud/examples/securitycenter/snippets/bigqueryexport/GetBigQueryExport.java:19, tag securitycenter_get_bigquery_export
• samples/snippets/src/main/java/com/google/cloud/examples/securitycenter/snippets/bigqueryexport/ListBigQueryExports.java:19, tag securitycenter_list_bigquery_export
• samples/snippets/src/main/java/com/google/cloud/examples/securitycenter/snippets/bigqueryexport/UpdateBigQueryExport.java:19, tag securitycenter_update_bigquery_export

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[catherinerosesantos]

Looks good! Just a few comments.

[Shabirmean]

I've reviewed this PR as part of the onboarding process to become a java-samples reviewer. @kurtisvg can you shadow review my reviews on this PR?

[Shabirmean]

Thank you for the changes. It seems like some tests are failing. PTAL!

[suztomo]

Memo:

com.google.api.gax.rpc.PermissionDeniedException: io.grpc.StatusRuntimeException: PERMISSION_DENIED: The caller does not have permission
	at com.google.api.gax.rpc.ApiExceptionFactory.createException(ApiExceptionFactory.java:53)
	at com.google.api.gax.grpc.GrpcApiExceptionFactory.create(GrpcApiExceptionFactory.java:72)
	at com.google.api.gax.grpc.GrpcApiExceptionFactory.create(GrpcApiExceptionFactory.java:60)
	at com.google.api.gax.grpc.GrpcExceptionCallable$ExceptionTransformingFuture.onFailure(GrpcExceptionCallable.java:97)
	at com.google.api.core.ApiFutures$1.onFailure(ApiFutures.java:68)
	at com.google.common.util.concurrent.Futures$CallbackListener.run(Futures.java:1133)
	at com.google.common.util.concurrent.DirectExecutor.execute(DirectExecutor.java:31)
	at com.google.common.util.concurrent.AbstractFuture.executeListener(AbstractFuture.java:1277)
	at com.google.common.util.concurrent.AbstractFuture.complete(AbstractFuture.java:1038)
	at com.google.common.util.concurrent.AbstractFuture.setException(AbstractFuture.java:808)
	at io.grpc.stub.ClientCalls$GrpcFuture.setException(ClientCalls.java:564)
	at io.grpc.stub.ClientCalls$UnaryStreamToFuture.onClose(ClientCalls.java:534)
	at io.grpc.PartialForwardingClientCallListener.onClose(PartialForwardingClientCallListener.java:39)
	at io.grpc.ForwardingClientCallListener.onClose(ForwardingClientCallListener.java:23)
	at io.grpc.ForwardingClientCallListener$SimpleForwardingClientCallListener.onClose(ForwardingClientCallListener.java:40)
	at com.google.api.gax.grpc.ChannelPool$ReleasingClientCall$1.onClose(ChannelPool.java:455)
	at io.grpc.internal.DelayedClientCall$DelayedListener$3.run(DelayedClientCall.java:463)
	at io.grpc.internal.DelayedClientCall$DelayedListener.delayOrExecute(DelayedClientCall.java:427)
	at io.grpc.internal.DelayedClientCall$DelayedListener.onClose(DelayedClientCall.java:460)
	at io.grpc.internal.ClientCallImpl.closeObserver(ClientCallImpl.java:562)
	at io.grpc.internal.ClientCallImpl.access$300(ClientCallImpl.java:70)
	at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInternal(ClientCallImpl.java:743)
	at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInContext(ClientCallImpl.java:722)
	at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)
	at io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:133)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:750)
	Suppressed: com.google.api.gax.rpc.AsyncTaskException: Asynchronous task failed
		at com.google.api.gax.rpc.ApiExceptions.callAndTranslateApiException(ApiExceptions.java:57)
		at com.google.api.gax.rpc.UnaryCallable.call(UnaryCallable.java:112)
		at com.google.cloud.securitycenter.v1.SecurityCenterClient.createBigQueryExport(SecurityCenterClient.java:4167)
		at com.google.cloud.examples.securitycenter.snippets.bigqueryexport.CreateBigQueryExport.createBigQueryExport(CreateBigQueryExport.java:83)
		at com.google.cloud.examples.securitycenter.snippets.BigQueryExportIT.setUp(BigQueryExportIT.java:76)
		at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
		at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
		at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
		at java.lang.reflect.Method.invoke(Method.java:498)

From .kokoro/presubmit/samples.cfg :

• GOOGLE_CLOUD_PROJECT: java-docs-samples-testing
• GOOGLE_APPLICATION_CREDENTIALS: secret_manager/java-docs-samples-service-account
• SECRET_MANAGER_KEYS: java-docs-samples-service-account,java-scc-samples-secrets

[suztomo]

Would "SECRET_MANAGER_KEYS" work for multiple keys? (The environment variable is plural but I'm not sure)

[Neenu1995]

The kokoro configuration looks correct. It will work with multiple keys.

[Shabirmean]

LGTM!

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