Currently it is possible for `HttpURLConnection` with the `Expect: 100-Continue` header to timeout awaiting for a server response. According to [RFC-7231](https://www.rfc-editor.org/rfc/rfc7231#section-5.1.1) a client `SHOULD NOT wait for an indefinite period before sending the message body`.
This PR changes the existing `expect100Continue` method to wait for a maximum of 5 seconds for a server response, this will be shorter if a timeout is set. If no response is received, the message is sent regardless. Tests have been added to account for different scenarios that currently timeout, and the changes have been tested against tiers 1,2 and 3. ------------- Commit messages: - further cleanup - cleanup and formatting - Fix for 100-continue hanging Changes: https://git.openjdk.org/jdk/pull/13330/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13330&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8054022 Stats: 416 lines in 2 files changed: 411 ins; 2 del; 3 mod Patch: https://git.openjdk.org/jdk/pull/13330.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/13330/head:pull/13330 PR: https://git.openjdk.org/jdk/pull/13330
