4.0.0 RC9

Note: This is a pre-release, there might be breaking changes in the final stable version.

• Added EventListener with additional responsibilities for ConnectionPool, Stream and DelegateHttpClient implementations.
• Added LimitedConnectionPool to limit concurrent requests per host
• Added LogHttpArchive allowing to inspect request timings visually
• Changed HttpClient to be a final class instead of an interface
• Changed redirect policy to only follow automatically with GET requests
• Application interceptors doing retries or follow-up requests must now manually clone the request if they wish to reuse it. Previously any HttpClient implementation was required to automatically clone at every layer.
• Http1Connection::__construct() requires an instance of EncryptableSocket instead of Socket now.
• Http1Connection reuses connections without explicit keep-alive header for idempotent requests now.
• Pushed requests validate the authority automatically now.
• Renamed IfOrigin to MatchOrigin and changed the implementation to map multiple origins.
• Requests can now set an upgrade handler to opt-into connection upgrades, e.g. for WebSocket connections or CONNECT tunnels.
• Removed default interceptors from PooledHttpClient and moved them into HttpClientBuilder
• Removed pings on idle Http2Connection::request() improving the overall latency.
• Removed ConditionalInterceptor
• Renamed Request::getPushCallable() to Request::getPushHandler()
• Renamed Request::onPush() to Request::setPushHandler()
• Renamed DefaultConnectionPool to UnlimitedConnectionPool
• 1XX responses are properly skipped now.
• Removed Connection::MAX_KEEP_ALIVE_TIMEOUT constant.
• Removed ConnectionPool::getProtocolVersions()