RFR: 8255583: Investigate creating a test to trigger the condition in KeepAliveStreamCleaner

[Conor Cleary]

The KeepAliveStreamCleaner in sun.net.ww.http package had been previously seen to fail with an IllegalMonitorStateException. This failure was caused by the use of `wait()` in a non synchronized block. This failure was mitigated through use of `await()` instead as is shown below (code can be viewed on L119 in src/java.base/share/classes/sun/net/www/http/KeepAliveStreamCleaner.java).

...
long timeout = TIMEOUT;
    while ((kace = poll()) == null) {
            waiter.await(timeout, TimeUnit.MILLISECONDS); 
...
While the code throwing the exception was fixed, a regression test was not made. So this patch adds a simple white-box test which calls the KeepAliveStreamCleaner's run method. `waiter.wait()` should always fail if not used in a synchronized block or method, so the test verifies that it is not used.

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Commit messages:
 - 8255583: Updated copyright notes
 - 8255583: Investigate creating a test to trigger the condition in KeepAliveStreamCleaner

Changes: https://git.openjdk.java.net/jdk/pull/1659/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1659&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255583
  Stats: 49 lines in 2 files changed: 42 ins; 6 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1659.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1659/head:pull/1659

PR: https://git.openjdk.java.net/jdk/pull/1659