use openjdk11 instead of oraclejdk11

Author: stefanseifert

.travis.yml

@@ -21,15 +21,15 @@ language: java
 
 jdk:
 - oraclejdk8
-- oraclejdk11
+- openjdk11
 
 # Make sure travis can use container-based infrastructure
 sudo: false
 
 install: "mvn -s ./.travis.maven-settings.xml clean"
 
 script:
-- "mvn -s ./.travis.maven-settings.xml -Pcontinuous-integration -U -Dmaven.javadoc.skip=true install"
+- "mvn -s ./.travis.maven-settings.xml -Pcontinuous-integration -U install"
 # Remove wcm.io artefacts from repository before cache
 - rm -rf $HOME/.m2/repository/io/wcm