RFR: 8318150: StaticProxySelector.select should not throw NullPointerExceptions [v2]

[Daniel Jeliński]

> `ProxySelector.select` and `connectFailed` methods should throw `IllegalArgumentException`s on null parameters.
> 
> Additionally, the `select` method doesn't need to be synchronized - the selector is immutable.
> 
> Tier2 green.

Daniel Jeliński has updated the pull request incrementally with one additional commit since the last revision:

  Use equalsIgnoreCase

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16199/files
  - new: https://git.openjdk.org/jdk/pull/16199/files/6ed6a983..66c79fa4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16199&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16199&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16199.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16199/head:pull/16199

PR: https://git.openjdk.org/jdk/pull/16199