**Issue** A recent fix for [JDK-8263031](https://bugs.openjdk.java.net/browse/JDK-8263031), which addressed the httpclient being unable to properly process Http/2 PushPromise frames followed by continuations caused intermittent failures of the test. This was cause by two seperate problems.
- Firstly, on the client side, `Http2Connection.processFrame` did not a check for whether or not a Continuation was to be expected early on in the method resulting in frames other than the expected Continuation Frame being incorrectly processed. In Http/2, when a Continuation Frame is expected, no other type of frame should be processed without a connection error of type PROTOCOL_ERROR being thrown. - Secondly, `Http2TestConnection.handlePush` had no guards around response headers and data frames being sent before a continuation is sent which resulted in the intermittent nature of this timeout. **Proposed Solution** The test class `OutgoingPushPromise` was modified to contain a list of Continuation Frames as required rather than the Continuations being scheduled to send in the test itself. This prevents the situation of unexpected frames being sent before a Continuation Frame was meant to arrive. In addition to the above, Http2Connection was modified to ensure that a connection error of type PROTOCOL_ERROR is thrown if a frame other than a Continuation arrives at the client unexpectedly. ------------- Commit messages: - 8284585: PushPromiseContinuation test fails intermittently in timeout Changes: https://git.openjdk.java.net/jdk/pull/8518/files Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8518&range=00 Issue: https://bugs.openjdk.java.net/browse/JDK-8284585 Stats: 63 lines in 4 files changed: 43 ins; 17 del; 3 mod Patch: https://git.openjdk.java.net/jdk/pull/8518.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/8518/head:pull/8518 PR: https://git.openjdk.java.net/jdk/pull/8518
