Jenkins Gradle Changelog Init Script, place this in ~/.gradle/init.d/changelog.gradle on your Jenkins server. Projects can simply call 'project.changelog' to get the changes for the current build.

changelog-auth.gradle

def buildUrl = System.getenv().BUILD_URL

if (buildUrl != null) {

    def auth = "<USER>:<APITOKEN>".getBytes().encodeBase64().toString()
    def url = new URL("$buildUrl/api/xml?depth=20").openConnection()
    url.setRequestProperty("Authorization", "Basic " + auth)
    String data = url.getInputStream().text

    def changelog = ""
    def xml = new XmlSlurper().parseText(data)

    xml.changeSet.item.each { change ->
        changelog += "$change.author.fullName: $change.msg" + '\n'
    }

    allprojects {
        project.ext.changelog = changelog
    }
}