Idea: tool similar to #1974 but for library developers to check compatibility

[suztomo]

A tool for the library developers to test library compatibility with other members of the LTS BOM.

• Manual work
  1. A library developer checkouts cloud-opensource-java repository
  2. The library developer modifies their library's tag in the YAML file (example) and install the BOM locally.
  3. The library developer runs the LtsRuntimeCompatibilityTest.
• Shell Script for the library developer to automate above
  Input: Maven coordinates
• GitHub Actions? It can specify branches. Usually it's master but for lts it should have some pattern. https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#onpushpull_requestbranchestags

 on:
   push:
     branches:
     - master
 pull_request:

c.f., #1974 is a tool for LTS BOM maintainers (us) to confirm the compatibility before publishing a LTS BOM.

Document: go/lts-library-test