any update on this?

It would be better to put this in a new function core.getCommaSeparatedInput() or core.getJsonInput().

People might already be using core.getMultilineInput() with list items that contain commas, so it's not safe to start treating commas as a list separator retrospectively.

- uses: myaction
  with:
    multiline-param: |
      item1, with comma
      item2 no comma
      item3, with, several, commas

This list has 3 items according to the current implementation, but your code would parse it as 7 items, potentially breaking the workflow.

It would be better to put this in a new function core.getCommaSeparatedInput() or core.getJsonInput().

People might already be using core.getMultilineInput() with list items that contain commas, so it's not safe to start treating commas as a list separator retrospectively.

- uses: myaction
  with:
    multiline-param: |
      item1, with comma
      item2 no comma
      item3, with, several, commas

This list has 3 items according to the current implementation, but your code would parse it as 7 items, potentially breaking the workflow.

Good comment 👍🏻! I've opened issue #1566 to tackle your concerns. Regarding getCommaSeparatedInput, we could also introduce a more versatile getJsonInput function. Unfortunately, I do not have the time right now to implement this 😅.

@rickstaa I implemented the core.getListInput (comma or new lines separated) in #1926, so if you dont have time to implement it yourself you can review the mentioned PR