fix(security_center): Rename region tag security_center_list_findings_within_time_range and move sample into security_command_center folder

[Kef131]

Description

Fixes # b/517939862

Updated the region tag from securitycenter_list_findings_at_time to securitycenter_list_findings_within_time_range in FindingSnippets.java. Also Moved all snippets from securitycenter into security-command-center.

• Fixed errors already present on security-command-center folder: When the tests attempted to iterate over lazy-loaded PagedResponse (used a try-with-resources block to create the SecurityCenterManagementClient client), after the helper method had exited, the client was already closed and its internal executor was terminated, resulting in the RejectedExecutionException. Then modified the 7 helper list classes in management/api to return an ImmutableList of the results rather than the lazy-loaded PagedResponse object.

Extra info for reviewers and for history

The region tag is still located in https://github.com/googleapis/google-cloud-java/blob/40f72f78e6781170c7f552b8fc18d242b29de625/google-cloud-examples/src/main/java/com/google/cloud/examples/securitycenter/snippets/FindingSnippets.java, google-cloud-java repo which is automatically collected to create the sampler, once this tag is renamed I can then modify the metadata to rename the previous region tag, this would remove the reference to the other repo by DKG and then obtain the one from java-docs-samples.

Checklist

• I have followed Sample Format Guide
• pom.xml parent set to latest shared-configuration
• Appropriate changes to README are included in PR
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• Tests pass: mvn clean verify required (Integration tests are skipped during compile using -DskipTests since they require live organization credentials, but all main and test code compiles successfully)
• Lint passes: mvn -P lint checkstyle:check required
• Static Analysis: mvn -P lint clean compile pmd:cpd-check spotbugs:check advisory only (Static analysis fails under JDK 25 environment due to ErrorProne plugin compatibility issues with jdk.compiler module exports)
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

[gemini-code-assist]

Code Review

This pull request updates the region tags in FindingSnippets.java to securitycenter_list_findings_within_time_range and removes an unused Maven project file. The reviewer points out that the method name listFindingsAtTime and its Javadoc should be updated to maintain consistency with the renamed region tag.

[amcolin]

LGTM