RFR: JDK-8285504 Minor cleanup could be done in javax.net

[Mark Powers]

https://bugs.openjdk.java.net/browse/JDK-8285504

JDK-8273046 is the umbrella bug for this bug. The changes were too large for a single code review, so it was decided to split into smaller chunks. This is one such chunk: 

open/src/java.base/share/classes/java/net

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Commit messages:
 - second iteration
 - Merge
 - Merge
 - first iteration

Changes: https://git.openjdk.java.net/jdk/pull/8384/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8384&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8285504
  Stats: 128 lines in 20 files changed: 1 ins; 21 del; 106 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8384.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8384/head:pull/8384

PR: https://git.openjdk.java.net/jdk/pull/8384