RFR: 8256461: AbstractFileSystemProvider.getSunPathForSocketCall for empty Path returns '.'

[Michael McMahon]

Could I get the following change reviewed please? 

The problem results from AbstractFileSystemProvider.getSunPathForSocketCall  returning a path of '.' when given an empty path argument. The socket API needs an empty path byte[] in this situation. It causes a BindException which is actually correct, but the error message is confusing because "." always exists and the error message is saying 'path already exists' when the actual error is that server socket channels cannot be bound to the empty path.

Thanks,
Michael.

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Commit messages:
 - windows build error
 - remove TABs
 - Merge branch 'master' into JDK-8256461-AbstractFileSystemProvider
 - added a test
 - initial fix
 - spec update after Alan's comments
 - Merge branch 'master' into 8255758-spec-change
 - net-properties.html change only. src apidoc change to come
 - update to net-properties.html
 - 8255758: JEP 380 spec clarifications

Changes: https://git.openjdk.java.net/jdk/pull/1258/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1258&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256461
  Stats: 60 lines in 4 files changed: 60 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1258.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1258/head:pull/1258

PR: https://git.openjdk.java.net/jdk/pull/1258