Switch Travis to bionic

.travis.yml

@@ -1,5 +1,7 @@
+# TravisCI is used mainly for SonarCloud and Coveralls quality integrations
+
 language: java
-dist: xenial
+dist: bionic
 sudo: false
 
 # required for SonarCloud
@@ -10,9 +12,6 @@ jdk:
   - openjdk8
   - openjdk11
 
-# TravisCI build is running only for coveralls.io/Coverage
-# Test verification pipeline is on ci.jenkins.io
-
 install: skip       # skip install phase as no deps are required
 
 # enable-jacoco profile is coming from the parent pom: