Yeah, that would be a nice first step. But I think we could also improve the List constructor by keeping the exceptions in cause and suppressed. That would be nicer than totally losing them in this case (having them in the message is nice but it's a bit limited IMHO).

But, AFAIK, in the case we had with the OpenLiberty people, we are in the second case you mention i.e. AfterDeploymentValidation.addDeploymentProblem() using the List constructor even if there is only one error.