Remove JDK11 build.
-buildPlugin(jdkVersions: [8, 11],
- checkstyle: [qualityGates: [[threshold: 1, type: 'NEW', unstable: true]]],
+buildPlugin(checkstyle: [qualityGates: [[threshold: 1, type: 'NEW', unstable: true]]],
pmd: [qualityGates: [[threshold: 1, type: 'NEW', unstable: true]]])
