The existing TCK test org.eclipse.microprofile.rest.client.tck.EntityPartTest only exercises the synchronous call path and employs a filter that forces an abort in order to return success or failure. As a result, it does not allow for a full end‑to‑end test, so a complete run never takes place. This is a gap.
Moreover, there is no asynchronous variant of EntityPartTest, which leads to a testing gap in multipart behavior for async clients.

This issue is being created to address the following:

Update EntityPartTest to perform a full server‑side process and remove the filter.

Add a new test, called AsyncEntityPartTest, to exercise the asynchronous call path with a full server process.