RFR: 8343791: Socket.connect API should document whether the socket will be closed when hostname resolution fails or another error occurs [v4]

[Volkan Yazıcı]

> This PR, addressing 8343791, enhances `Socket#connect()` and effectively makes it close the `Socket` if `SocketImpl#connect()` fails with a
> 
> 1. `SocketTimeoutException`
> 2. `InterruptedIOException` in an interrupted vthread
> 3. `IOException` that is *not* an `UnknownHostException`
> 
> On the other hand, socket will *not* be closed if `SocketImpl#connect()` fails with a
> 
> * `InterruptedIOException` that is neither a `SocketTimeoutException`, nor from an interrupted vthread
> * `UnknownHostException`
> 
> Note that in case of an `UHE`, `Socket` and `SocketImpl` states will match, i.e., `SOCKET_CREATED`.
> 
> One peculiar detail retained from the old code is that `InterruptedIOException` is causing a socket close *iff* we are in an interrupted vhtread. (Guess: To ensure resources within a vthread task scope is released in tandem with the completion of the scope?) I don't know why other `InterruptedIOException` cases are left out.
> 
> Before "8284161: Implementation of Virtual Threads (Preview)" (9583e365), `connect()` failures were getting propagated untouched. 8284161 added the logic to throw `SocketException("Closed by interrupt")` *and* close the socket if `InterruptedIOException` is caught in an interrupted vthread.
> 
> Judging from the last state of the `Socket#connect()` javadoc, I find it very difficult to wrap ones mind around in which cases the socket will be closed. As a user, I'd be in favor of a simpler approach – e.g., `try { socketImpl.connect(); } catch (Exception e) { closeQuietly(e); throw e }` – at the cost of incorporating a backward incompatible behavioral change. I would appreciate your advice on how shall we proceed further.

Volkan Yazıcı has updated the pull request incrementally with one additional commit since the last revision:

  Apply review feedback from Alan

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/22160/files
  - new: https://git.openjdk.org/jdk/pull/22160/files/435f15d7..7e633d8d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22160&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22160&range=02-03

  Stats: 20 lines in 1 file changed: 9 ins; 4 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/22160.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22160/head:pull/22160

PR: https://git.openjdk.org/jdk/pull/22160