Test againt Java 20 on CI.

See #489.

Jenkinsfile

@@ -1,7 +1,7 @@
 def p = [:]
 node {
-    checkout scm
+	checkout scm
-    p = readProperties interpolate: true, file: 'ci/pipeline.properties'
+	p = readProperties interpolate: true, file: 'ci/pipeline.properties'
 }
 
 pipeline {
@@ -18,7 +18,7 @@ pipeline {
 	}
 
 	stages {
-		stage("test: baseline (Java 17)") {
+		stage("test: baseline (main)") {
 			when {
 				beforeAgent(true)
 				anyOf {
@@ -42,6 +42,34 @@ pipeline {
 			}
 		}
 
+		stage("Test other configurations") {
+			when {
+				beforeAgent(true)
+				allOf {
+					branch(pattern: "main|(\\d\\.\\d\\.x)", comparator: "REGEXP")
+					not { triggeredBy 'UpstreamCause' }
+				}
+			}
+			parallel {
+				stage("test: baseline (next)") {
+					agent {
+						label 'data'
+					}
+					options { timeout(time: 30, unit: 'MINUTES') }
+					environment {
+						ARTIFACTORY = credentials("${p['artifactory.credentials']}")
+					}
+					steps {
+						script {
+							docker.image(p['docker.java.next.image']).inside(p['docker.java.inside.basic']) {
+								sh 'MAVEN_OPTS="-Duser.name=jenkins -Duser.home=/tmp/jenkins-home" ./mvnw -s settings.xml clean dependency:list test -Dsort -U -B'
+							}
+						}
+					}
+				}
+			}
+		}
+
 		stage('Release to artifactory') {
 			when {
 				beforeAgent(true)