Update the Endpoints getting-started sample

[wmwong]

In which file did you encounter the issue?

java-docs-samples/endpoints/getting-started

Did you change the file? If so, how?

No

Describe the issue

This PR was a copy and extension of the existing getting-started sample:
#627

The comments in the PR also apply to the existing getting-started sample and the same fixes should be made.

[wmwong]

Fixed in #642