Wait to announce the release if it is not available in Maven Central yet

[shakuzen]

Even though our release process may have finished, it can take some time after that before Maven Central is able to serve the artifacts published. It would be ideal if the post-release workflow polls Maven Central to ensure that artifacts for the released version are already available before making the release announcement. Typically it does not take more than 10-20 minutes for artifacts to be available, but we may run into timeout issues with such a long-running action polling Maven Central.

[snicoll]

With the new central API, waiting for the artifacts to be available (i.e. polling for a GET on a released artifact) is no longer necessary if you watch for the outcome of the deployment.

Our GitHub action does that automatically and will only complete once it knows about the outcome (or fail if hit a timeout doing so). See Deployer for more details.