test failures with TLS 1.3 / Java 11

Java 11 enables/uses TLS 1.3 by default, and some of the SSL tests fail in this scenario. Debugging [eventually] showed that the updated handshake behaviour can result in further input accumulating in the input buffer while output/wrap is needed to continue the handshake, due to the manner in which the SSLEngine is used by the transport but in particular also with how the tests use the transport meaning the following input can't get processed (as no new input follows it to prompt it) and the handshake doesn't complete. Some ad-hoc non-test usage didn't encounter the issue but could theoretically.