Fix advertised JNLP Port

As far as I can figure, the /TcpSlaveAgentListener/ endpoint headers
tell the slaves what the JNLP port is. When I'm running jenkins behind a
proxy (marathon using the mesos plugin, which bridged networking), even
though I was setting the advertised port per a thread[1], it was not
accurately being returned in the header. This patch fixes that.

[1] https://groups.google.com/d/topic/jenkins-mesos/qUrXpDY07TQ/discussion

initializer annotation on instance methods

... which is done by looking for locating & instantiating ExtensionFinders.

This simplifies typical usage of them.

... or else it'll keep running. This can be seen as a large number of zombie threads like the following in the unit test:

"NioChannelHub keys=0 gen=0: Computer.threadPoolForRemoting [#250]" daemon prio=10 tid=0x00007f793d841000 nid=0x3cc1 runnable [0x00007f78e2665000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
        at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:228)
        at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:81)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:87)
        - locked <0x00000000c50d46d8> (a sun.nio.ch.Util$2)
        - locked <0x00000000c50d46e8> (a java.util.Collections$UnmodifiableSet)
        - locked <0x00000000c50d4690> (a sun.nio.ch.EPollSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:98)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:102)
        at org.jenkinsci.remoting.nio.NioChannelHub.run(NioChannelHub.java:542)
        at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
        at java.util.concurrent.FutureTask.run(FutureTask.java:166)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:722)

Be quiet

[JENKINS-33546] [JENKINS-33605] Back to Stapler 1.239

Add the .mvn directory and set default Xmx value

Fix typo in hudson/tools/label.jelly

Using the new feature introduced in Maven 3.3.1.
See
https://maven.apache.org/docs/3.3.1/release-notes.html#JVM_and_Command_Line_Options
for more details.

Possibly a long term better solution/first encounter for newcomers. When
people can't build Jenkins because of wrong default memory settings.
Like https://goo.gl/Co9kye

The "Xmx800m" was chosen after looking at last successful ci.j.o builds.
Max memory displayed by Maven being ~730MB. So putting 800 to leave the
build some room so that the GC has less chance to have to chime in too
often.

Make Fingerprint's XSTREAM field public

[FIX WEBSITE-147] Make changelog ratings work on jenkins.io

[FIX WEBSITE-147]

Some plugins needs to register compatibility alias etc for
their FingerprintFacets.

[FIXED JENKINS-33693] Do not hardcode .bat extension.

This reverts commit 0d0d2a9c.

[FIXED JENKINS-33681] Plugin filters were failing to be removed and blocking restart

[JENKINS-33467] Clarifying that CauseAction.getCauses is immutable

As the default maven command is on the path we can not hard code the
command to mvn.bat as since maven 3.something it has been mvn.cmd

As this is on the path we can just use mvn and let Windows do its thing
with PATHEXT which will has both .BAT and .CMD by default.

This fixes ATH failures when the ATH is run on windows.

[INFRA-588] Upgrade + Remove inherited values