[securitycenter] v2 client's apiEndpoint property is wrong when a regional endpoint is specified

[hegemonic]

Please make sure you have searched for information in the following guides.

• Search the issues already opened: https://github.com/GoogleCloudPlatform/google-cloud-node/issues
• Search StackOverflow: http://stackoverflow.com/questions/tagged/google-cloud-platform+node.js
• Check our Troubleshooting guide: https://googlecloudplatform.github.io/google-cloud-node/#/docs/guides/troubleshooting
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A screenshot that you have tested with "Try this API".

n/a

Link to the code that reproduces this issue. A link to a public Github Repository or gist with a minimal reproduction.

https://gist.github.com/hegemonic/cf807026d8b83c14aa0b225b16967599

A step-by-step description of how to reproduce the issue, based on the linked reproduction.

Run the code. It creates a v2 SecurityCenterClient; sets the apiEndpoint to securitycenter.me-central2.rep.googleapis.com; and prints the expected and actual apiEndpoint for the client.

A clear and concise description of what the bug is, and what you expected to happen.

The code prints the following:

expected apiEndpoint: securitycenter.me-central2.rep.googleapis.com
actual apiEndpoint: securitycenter.googleapis.com
client._opts.apiEndpoint: securitycenter.me-central2.rep.googleapis.com

I expected it to print the following:

expected apiEndpoint: securitycenter.me-central2.rep.googleapis.com
actual apiEndpoint: securitycenter.me-central2.rep.googleapis.com
client._opts.apiEndpoint: securitycenter.me-central2.rep.googleapis.com

A clear and concise description WHY you expect this behavior, i.e., was it a recent change, there is documentation that points to this behavior, etc. **

• If I specify an API endpoint, the client object shouldn't say that it's using the default endpoint.
• You shouldn't need to look at private properties to figure out which endpoint the client is using.

[github-actions]

Issue was opened with an invalid reproduction link. Please make sure the repository is a valid, publicly-accessible github repository, and make sure the url is complete (example: https://github.com/googleapis/google-cloud-node)

[hegemonic]

@sofisl Why was this bug closed? I provided a valid link to a publicly visible gist.