Building on JDK11 [GEOS-9082]

[aaime]

Depends on geotools/geotools#2100 and GeoWebCache/geowebcache#695

See
https://osgeo-org.atlassian.net/browse/GEOS-9082

[aaime]

Failure on Windows is random, but tends to happen a lot more o Win than on Linux:

[00:22:15] Tests run: 48, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 193.033 sec <<< FAILURE!
[00:22:15] testAutomaticTruncationLayerStyleChange(org.geoserver.gwc.GWCIntegrationTest)  Time elapsed: 2369 sec  <<< FAILURE!
[00:22:15] java.lang.AssertionError: 
[00:22:15] Expected: equalToIgnoringCase("MISS")
[00:22:15]      but: was HIT
[00:22:15] 	at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:20)
[00:22:15] 	at org.junit.Assert.assertThat(Assert.java:865)
[00:22:15] 	at org.junit.Assert.assertThat(Assert.java:832)
[00:22:15] 	at org.geoserver.gwc.GWCIntegrationTest.testAutomaticTruncationLayerStyleChange(GWCIntegrationTest.java:793)

[aaime]

Turned into the jdk11 branch, closing the PR