RFR: 8235139: Deprecate the socket impl factory mechanism [v4]

[Patrick Concannon]

> Hi,
> 
> Could someone please review my proposed changeset for JDK-8235139: '`Remove the socket impl factory mechanism`' ?
> 
> These changes propose to deprecate (for the eventual removal) the API points for statically configuring a system-wide factory for the `Socket`, `ServerSocket`, and `DatagramSocket` types in the `java.net package`. Specifically, the following:
> 
> **Methods**:
> - `static void Socket.setSocketImplFactory​(SocketImplFactory fac)`
> - `static void ServerSocket.setSocketFactory​(SocketImplFactory fac)`
> - `static void DatagramSocket.setDatagramSocketImplFactory​(DatagramSocketImplFactory fac)`
> 
> **Types**:
> - `java.net SocketImplFactory`
> - `java.net DatagramSocketImplFactory`
> 
> The CSR for[ JDK-8220494](https://bugs.openjdk.java.net/browse/JDK-8220494) contains some verbiage about the potential
> issues that setting factories can have, and alludes to their possible
> future removal. 
> 
> The CSR for this issue can be viewed here: https://bugs.openjdk.java.net/browse/JDK-8261228
> 
> Kind regards,
> Patrick

Patrick Concannon has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:

 - 8235139: Updated @deprecated message for Socket/ServerSocket with more accurate suggestion for alternative
 - Merge remote-tracking branch 'origin/master' into JDK-8235139
 - 8235139: Removed @Deprecated annotation from factory fields
 - Merge remote-tracking branch 'origin/master' into JDK-8235139
 - 8235139: Updated @deprecated text for setSocketFactory methods in Socket and ServerSocket
 - Merge remote-tracking branch 'origin/master' into JDK-8235139
 - 8235139: Remove the socket impl factory mechanism

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2375/files
  - new: https://git.openjdk.java.net/jdk/pull/2375/files/9d789083..3a894322

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2375&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2375&range=02-03

  Stats: 143 lines in 10 files changed: 32 ins; 2 del; 109 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2375.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2375/head:pull/2375

PR: https://git.openjdk.java.net/jdk/pull/2375