RFR: 8325579: Inconsistent behavior in com.sun.jndi.ldap.Connection::createSocket [v3]

[Christoph Langer]

> During analysing a customer case I figured out that we have an inconsistency between documentation and actual behavior in class com.sun.jndi.ldap.Connection. The [method documentation of com.sun.jndi.ldap.Connection::createSocket](https://github.com/openjdk/jdk/blob/3ebe6c192a5dd5cc46ae2d263713c9ff38cd46bb/src/java.naming/share/classes/com/sun/jndi/ldap/Connection.java#L281) states: "If a timeout is supplied but unconnected sockets are not supported then the timeout is ignored and a connected socket is created."
> 
> This, however does not happen. If a SocketFactory would not support unconnected sockets, it would likely throw a SocketException in [SocketFactory::createSocket()](https://github.com/openjdk/jdk/blob/6303c0e7136436a2d3cb6043b88edf788c0067cc/src/java.base/share/classes/javax/net/SocketFactory.java#L123). And since [the code](https://github.com/openjdk/jdk/blob/3ebe6c192a5dd5cc46ae2d263713c9ff38cd46bb/src/java.naming/share/classes/com/sun/jndi/ldap/Connection.java#L336) does not check for this behavior, a connection with timeout value through a SocketFactory that does not support unconnected sockets would simply fail with an IOException.
> 
> So we should either make the code adhere to what is documented or adapt the documentation to the actual behavior.
> 
> I hereby try to fix the connect coding. Alternatively, we could also adapt the description - I have no strong opinion. What do the experts suggest?

Christoph Langer has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:

 - Enhance test
 - JDK-8325579

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Changes: https://git.openjdk.org/jdk/pull/17797/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17797&range=02
  Stats: 235 lines in 3 files changed: 128 ins; 29 del; 78 mod
  Patch: https://git.openjdk.org/jdk/pull/17797.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17797/head:pull/17797

PR: https://git.openjdk.org/jdk/pull/17797