https://issues.jenkins-ci.org/browse/JENKINS-48523  added support to the tag when condition with the comparator. 

At the moment, the changeset when condition does support GLOB, but no REGEXP patterns. Let's standardize the changeset condition format as done with the tag condition.

when {
    changeset "**/*.java"
}
when {
    changeset pattern: "**/*.java", comparator: "GLOB"
} 
when {
    changeset pattern: ".*\\.java", comparator: "REGEXP"
}