These two classes should no longer be used once HTTP/1.1 uses the asynchronous connections. They can be removed. Once this is done, then the synchronous method read() and readImpl() can also be removed from HttpConnection and its subclasses.
JDK-8186957Cleanup: Remove temporary AbstractAsyncConnection (merge it back with HttpConnection)
is blocked by
JDK-8186954Prototype changing the httpclient Http1Exchange/Http1Response to use asynchronous connections