[jdk11u-dev] RFR: 8220083: Remove hard-coded 127.0.0.1 loopback address in JDK networking tests

[Goetz Lindenmaier]

I backport this test improvement as prereq of 8223145 Replace wildcard address with loopback or local host in tests - part 1

I had to resolve the following files:

test/jdk/com/sun/net/httpserver/bugs/6725892/Test.java
Copyright

test/jdk/java/net/SocketOption/TcpKeepAliveTest.java
Changes already backported. Skipped.

test/jdk/java/nio/channels/SocketChannel/CloseRegisteredChannel.java
Resolved due to context.

test/jdk/sun/net/www/protocol/http/TunnelThroughProxy.java
Patch skipped because "8216986: Remove unused code from SocksSocketImpl" not in 11.

SendFailed.java
I had to add import for InetAddress to make it work.

Tests all pass.

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Commit messages:
 - Backport ef9ce3be1e33f1a45a6d8fbcbe3d4ceffcf7c4ce

Changes: https://git.openjdk.org/jdk11u-dev/pull/2222/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2222&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8220083
  Stats: 69 lines in 25 files changed: 10 ins; 4 del; 55 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2222.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2222/head:pull/2222

PR: https://git.openjdk.org/jdk11u-dev/pull/2222