Merge pull request jenkinsci#827 from jenkinsci/add-jdk11-testing

Enable CI testing of the jdk11 variant

Jenkinsfile

@@ -31,7 +31,7 @@ nodeWithTimeout('docker') {
             sh "make prepare-test"
         }
 
-        def labels = ['debian', 'slim', 'alpine']
+        def labels = ['debian', 'slim', 'alpine', 'jdk11']
         def builders = [:]
         for (x in labels) {
             def label = x
@@ -72,4 +72,4 @@ void nodeWithTimeout(String label, def body) {
             body.call()
         }
     }
-}
+}