Replace all Ubuntu 16.04 with Ubuntu18.04 image
Change-Id: I86b84957145f7c1f253d3158e42e015c322788eb
diff --git a/jjb/pipeline/onos-app-release.groovy b/jjb/pipeline/onos-app-release.groovy
index ee14658..f8d87de 100644
--- a/jjb/pipeline/onos-app-release.groovy
+++ b/jjb/pipeline/onos-app-release.groovy
@@ -42,7 +42,7 @@
// TODO: use the declarative pipeline syntax, like all other groovy files.
// This implementation is based on the legacy cord-onos-publisher/Jenkinsfile.release
-node ('ubuntu16.04-basebuild-1c-2g') {
+node ('ubuntu18.04-basebuild-1c-2g') {
sh 'echo Releasing ' + appRepo + ' repository on ' + branch + ' branch'
sh 'echo Releasing version ' + version + ' with API version ' + apiVersion + ' and starting ' + nextVersion + '-SNAPSHOT with API version ' + nextApiVersion + '-SNAPSHOT'