When is hashFiles() actually needed?

[marco-brandizi]

Hi all,

I see hashFiles() used a lot to define cache keys, and I've used it myself for years, copy-pasting from the Maven example:

    - name: Cache Maven packages
      uses: actions/cache@v3
      with:
        path: ~/.m2
        key: ${{ runner.os }}-m2-v1-${{ hashFiles('**/pom.xml') }}
        restore-keys: ${{ runner.os }}-m2-v1-

However, in the GH interface, I've noticed I've several caches that maybe don't need to be created.

I mean, I run the build with mvn --update-snapshots ..., so, even if it restores always the same cache, no matter if the dependencies are changed, it should still work fine, for Maven keeps checking (quickly) what has changed, re-download new updates and downloads dependencies it doesn't find in the cached repo. So, it should be fine to have just one cache and one key (per OS).

Am I right? Would something like key: ${{ runner.os }}-m2-v1 still work, in the situation above? Or am I missing some possible troubles?

Many thanks in advance.