diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8436c0a2..5548b38b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -26,18 +26,18 @@ jobs:
 
     steps:
       - name: Checkout Source
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
         with:
           fetch-depth: 0
 
       - name: Setup Java
-        uses: actions/setup-java@v4
+        uses: actions/setup-java@v5
         with:
           distribution: 'temurin'
-          java-version: 17
+          java-version: 21
 
       - name: Setup Gradle
-        uses: gradle/actions/setup-gradle@v4
+        uses: gradle/actions/setup-gradle@v5
 
       - name: Check Branch
         run: |
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7bf031c3..1017bfc7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -65,6 +65,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Update `Gradle Wrapper` to 9.1.0 [#624](https://github.com/ie3-institute/OSMoGrid/issues/624)
 - Updated Ubuntu version to 24.04 and Python version to 3.13 in readthedocs.yml [#640](https://github.com/ie3-institute/OSMoGrid/issues/640)
 - Updated gradle version 9.2.1 new version  [#649](https://github.com/ie3-institute/OSMoGrid/issues/649)
+- Update to Java 21 [#620](https://github.com/ie3-institute/OSMoGrid/issues/620)
 
 ### Fixed
 - Fixed bug in `LvGridGeneratorSupport` [#388](https://github.com/ie3-institute/OSMoGrid/issues/388)
diff --git a/Jenkinsfile b/Jenkinsfile
deleted file mode 100644
index fd7f13df..00000000
--- a/Jenkinsfile
+++ /dev/null
@@ -1,687 +0,0 @@
-#!groovy
-
-/*
- * © 2021. TU Dortmund University,
- * Institute of Energy Systems, Energy Efficiency and Energy Economics,
- * Research group Distribution grid planning and operation
- */
-
-////////////////////////////////
-// general config values
-////////////////////////////////
-
-/* project configuration */
-String javaVersionId = 'jdk-17' // id that matches the java tool with the java version that should be used set as jenkins property
-
-/* git configuration */
-String projectName = 'OSMoGrid' // name of the repository, is case insensitive
-String orgName = 'ie3-institute' // name of the github organization
-String gitCheckoutUrl = "git@github.com:$orgName/${projectName}.git"
-String sshCredentialsId = '19f16959-8a0d-4a60-bd1f-5adb4572b702' // id that matches the ssh credentials to interact with the git set as jenkins property
-
-/* ci configuration */
-String sonarqubeProjectKey = 'edu.ie3:OSMoGrid' // sonarqube project key, case-sensitive
-String codeCovTokenId = 'osmogrid-codecov-token' // id that matches the code coverage token set as jenkins property
-
-/* maven central configuration */
-String mavenCentralCredentialsId = '87bfb2d4-7613-4816-9fe1-70dfd7e6dec2' // id that matches the maven central credentials set as jenkins property
-String mavenCentralSignKeyFileId = 'dc96216c-d20a-48ff-98c0-1c7ba096d08d' // id that matches the maven central sign key file set as jenkins property
-String mavenCentralSignKeyId = 'a1357827-1516-4fa2-ab8e-72cdea07a692' // id that matches the maven central sign key id set as jenkins property
-
-/**
- * pipeline configuration
- */
-
-/* setup pipeline properties */
-// dev and main need manual deploy capabilities
-if (env.BRANCH_NAME == "main" || env.BRANCH_NAME == "dev") {
-  constantBranchesProps()
-} else {
-  // all other branches need trigger capabilities for PRs
-  temporaryBranchesProps()
-}
-
-/**
- * pipeline
- */
-
-node {
-  ansiColor('xterm') {
-    try {
-      // set java version
-      setJavaVersion(javaVersionId)
-
-      // determine branch name that should be checked out
-      net.sf.json.JSONObject prJsonObj = getPRJsonObj(orgName, projectName, env.CHANGE_ID)
-      String currentBranchName = prJsonObj == null ? env.BRANCH_NAME : prJsonObj.head.ref
-      String targetBranchName = prJsonObj == null ? null : prJsonObj.base.ref
-
-      /* prs from forks require a special handling*/
-      String headGitCheckoutUrl = prJsonObj == null ? gitCheckoutUrl : prJsonObj.head.repo.ssh_url
-
-      // checkout scm
-      String commitHash = ""
-      stage('checkout') {
-        // commit hash from scm checkout
-        // https://www.theserverside.com/blog/Coffee-Talk-Java-News-Stories-and-Opinions/Complete-Jenkins-Git-environment-variables-list-for-batch-jobs-and-shell-script-builds
-        commitHash = gitCheckout(projectName, headGitCheckoutUrl, currentBranchName, sshCredentialsId).GIT_COMMIT
-      }
-
-      // set build display name
-      String displayNameBranchName = prFromFork() ? prJsonObj.head.repo.full_name : currentBranchName
-      currentBuild.displayName = determineDisplayName(displayNameBranchName, commitHash, orgName, projectName)
-
-      if (currentBranchName == "main") {
-        stage('handle dev pr') {
-          // normally main pipeline is only triggered by merge of release or hotfixes OR manually triggered
-          // if manually triggered for deploy, no PR should be created
-          if (params.deploy != "true") {
-            handleDevPr(sshCredentialsId, orgName, projectName, currentBranchName)
-          }
-        }
-      }
-
-      // version check
-      stage('version check') {
-        // version check can only be executed, if target branch is known (derived from a PR)
-        if (targetBranchName == "main" || targetBranchName == "dev") {
-          if (checkVersion(currentBranchName, targetBranchName, projectName, projectName, gitCheckoutUrl, headGitCheckoutUrl, sshCredentialsId) != 0)
-            error "Version check failed! See log for version differences."
-        } else if (targetBranchName == null) {
-          // if this branch is the dev branch, we can still do version check to compare if dev and main have the same semnatic version
-          if (env.BRANCH_NAME == "dev") {
-            if (checkVersion(currentBranchName, "main", projectName, projectName, gitCheckoutUrl, headGitCheckoutUrl, sshCredentialsId) != 0)
-              error "Version check failed! See log for version differences."
-          } else {
-            println "No PR for branch '$currentBranchName' exists. Cannot check versioning! Please create a PR to enable version check."
-          }
-        } else {
-          error "Target branch name '$targetBranchName' for merging is not supported! Please select either 'dev' or 'main' as " +
-              "target branch for merging!"
-        }
-      }
-
-      // test the project
-      stage('run tests') {
-
-        sh 'java -version'
-
-        gradle('--refresh-dependencies clean spotlessCheck pmdMain pmdTest spotbugsMain spotbugsTest test reportScoverage checkScoverage', projectName)
-
-        // due to an issue with openjdk-8 we use openjdk-11 for javadocs generation
-        sh(script: """set +x && cd $projectName""" + ''' set +x; ./gradlew clean javadoc''', returnStdout: true)
-      }
-
-      // sonarqube analysis
-      stage('sonarqube analysis') {
-        String sonarqubeCurrentBranchName = prFromFork() ? prJsonObj.head.repo.full_name : currentBranchName // forks needs to be handled differently
-        String sonarqubeCmd = determineSonarqubeGradleCmd(sonarqubeProjectKey, sonarqubeCurrentBranchName, targetBranchName, orgName, projectName, projectName)
-        withSonarQubeEnv() {
-          // will pick the global server connection from jenkins for sonarqube
-          gradle(sonarqubeCmd, projectName)
-        }
-      }
-
-      // sonarqube quality gate
-      stage("quality gate") {
-        timeout(time: 1, unit: 'HOURS') {
-          // just in case something goes wrong, pipeline will be killed after a timeout
-          def qg = waitForQualityGate() // reuse taskId previously collected by withSonarQubeEnv
-          if (qg.status != 'OK') {
-            error "Pipeline aborted due to quality gate failure: ${qg.status}"
-          }
-        }
-      }
-
-      // deploy stage only if branch is main or dev
-      if (env.BRANCH_NAME == "main" || env.BRANCH_NAME == "dev") {
-        stage('deploy') {
-          // determine project version
-          String projectVersion = sh(returnStdout: true, script: "set +x && cd ${projectName}; ./gradlew -q " +
-          "${(env.BRANCH_NAME == "dev") ? "devVersion" : "currentVersion"}").toString().trim()
-
-          // get the sonatype credentials stored in the jenkins secure keychain
-          withCredentials([
-            usernamePassword(credentialsId: mavenCentralCredentialsId, usernameVariable: 'mavencentral_username', passwordVariable: 'mavencentral_password'),
-            file(credentialsId: mavenCentralSignKeyFileId, variable: 'mavenCentralKeyFile'),
-            usernamePassword(credentialsId: mavenCentralSignKeyId, passwordVariable: 'signingPassword', usernameVariable: 'signingKeyId')
-          ]) {
-
-            /*
-             * IMPORTANT: Do not issue 'clean' in the following task
-             */
-            sh(
-                script: """set +x && cd $projectName""" +
-                ''' set +x; ./gradlew clean javadoc''',
-                returnStdout: true
-                )
-
-            String deployGradleTasks = "--refresh-dependencies test " +
-                "publish -Puser=${env.mavencentral_username} " +
-                "-Ppassword=${env.mavencentral_password} " +
-                "-Psigning.keyId=${env.signingKeyId} " +
-                "-Psigning.password=${env.signingPassword} " +
-                "-Psigning.secretKeyRingFile=${env.mavenCentralKeyFile} " +
-                "-PdeployVersion='$projectVersion'"
-
-            // see https://docs.gradle.org/6.0.1/release-notes.html "Publication of SHA256 and SHA512 checksums"
-            def preventSHACheckSums = "-Dorg.gradle.internal.publish.checksums.insecure=true"
-            gradle("${deployGradleTasks} $preventSHACheckSums", projectName)
-          }
-
-          if (env.BRANCH_NAME == "main") {
-            // create tag on main and push it to origin
-            createAndPushTagOnMain(projectName, sshCredentialsId)
-
-            // todo JH create github release
-
-            // deploy java docs
-            deployJavaDocs(projectName, sshCredentialsId, gitCheckoutUrl)
-          }
-        }
-      }
-
-      // post processing
-      stage('post processing') {
-
-        // publish reports
-        publishReports(projectName)
-
-        // call codecov.io
-        withCredentials([
-          string(credentialsId: codeCovTokenId, variable: 'codeCovToken')
-        ]) {
-          sh "curl -s https://codecov.io/bash | bash -s - -t ${env.codeCovToken} -C ${commitHash}"
-        }
-      }
-    } catch (Exception e) {
-      // set build result to failure
-      currentBuild.result = 'FAILURE'
-
-      // publish reports even on failure
-      publishReports(projectName)
-
-      // print exception
-      Date date = new Date()
-      println("[ERROR] [${date.format("dd/MM/yyyy")} - ${date.format("HH:mm:ss")}] " + e)
-    }
-  }
-}
-
-
-/**
- * pipeline stages - all methods require node context
- */
-
-def setJavaVersion(String javaVersionId) {
-  env.JAVA_HOME = "${tool javaVersionId}"
-  env.PATH = "${env.JAVA_HOME}/bin:${env.PATH}"
-}
-
-/* git interaction */
-
-def gitCheckout(String relativeTargetDir, String gitCheckoutUrl, String branch, String sshCredentialsId) {
-  checkout([
-    $class                           : 'GitSCM',
-    branches                         : [[name: branch]],
-    doGenerateSubmoduleConfigurations: false,
-    extensions                       : [
-      [$class: 'RelativeTargetDirectory', relativeTargetDir: relativeTargetDir]
-    ],
-    submoduleCfg                     : [],
-    userRemoteConfigs                : [
-      [credentialsId: sshCredentialsId, url: gitCheckoutUrl]
-    ]
-  ])
-}
-
-def handleDevPr(String sshCredentialsId, String orgName, String projectName, String currentBranchName) {
-  // get the latest merge string from git to derive latest commit hash + latest merge branch name
-  String gitLogLatestMergeString = ""
-  withCredentials([
-    sshUserPrivateKey(credentialsId: sshCredentialsId, keyFileVariable: 'sshKey')
-  ]) {
-    // cleanup to prepare repo
-    sh(script:
-    "set +x && cd $projectName && " +
-    "ssh-agent bash -c \"set +x && ssh-add $sshKey; " +
-    "git branch | grep -v \"$currentBranchName\" | xargs git branch -D;" + // deletes all local branches except main
-    "git fetch && git checkout $currentBranchName && git pull\"", returnStdout: false)
-
-    gitLogLatestMergeString = sh(script: "cd $projectName && set +x && git log --merges -n 1", returnStdout: true)
-  }
-
-  // only create pr if the last merge has been a hotfix or a release branch merge
-  boolean isHotfix = gitLogLatestMergeString.find("Merge pull request .+ from .*hotfix/\\pL{2}/#\\d+.*") ? true : false
-  boolean isRelease = gitLogLatestMergeString.find("Merge pull request .+ from .*rel/\\pL{2}/#\\d+.*") ? true : false
-
-  if (isHotfix || isRelease) {
-
-    // try to get hotfix first, if this fails try to get release
-    String latestMergeBranchName = ""
-    if (isHotfix) {
-      String hotfixRegex = "hotfix/\\pL{2}/#\\d+.*"
-      latestMergeBranchName = (gitLogLatestMergeString.find(hotfixRegex).trim() =~ hotfixRegex)[0]
-    } else {
-      String relRegex = "rel/\\pL{2}/#\\d+.*"
-      latestMergeBranchName = (gitLogLatestMergeString.find(relRegex).trim() =~ relRegex)[0]
-    }
-
-    // get the latest merge commit sha
-    String latestMergeCommitSHA = gitLogLatestMergeString.find("Merge: .* .*\n").trim().split(" ")[2]
-
-    // create new branch with same name as before + hand in a pull request for dev branch,
-    // if the branch already exists catch the exception because then we can just go on for a PR
-    try {
-      withCredentials([
-        sshUserPrivateKey(credentialsId: sshCredentialsId, keyFileVariable: 'sshKey')
-      ]) {
-        sh(script: "set +x && cd $projectName && " +
-        "ssh-agent bash -c \"set +x && ssh-add $sshKey; " +
-        "git fetch && git checkout $currentBranchName && git pull && " +
-        "git checkout -b $latestMergeBranchName $latestMergeCommitSHA && " +
-        "git push --set-upstream origin $latestMergeBranchName\"")
-      }
-    } catch (Exception e) {
-      println "No need to create a new branch. Can reuse old one."
-    }
-
-    // create PR on dev branch
-    withCredentials([
-      string(credentialsId: 'SimServCIDeveloperAccessTokenForWebhooks', variable: 'SimServCIToken')
-    ]) {
-      String issueId = (latestMergeBranchName =~ ".*(#\\d+).*")[0][1]
-      String prMessage = "CI generated PR for branch `$latestMergeBranchName` after merging it into `main`.\\n" +
-          "Please review, adapt and merge it into `dev`.\\nResolves $issueId."
-      String curlCmd = "set +x && " +
-          "curl -s -X POST -u johanneshiry:$SimServCIToken -H \"Accept: application/vnd.github.v3+json\"" +
-          " https://api.github.com/repos/$orgName/$projectName/pulls" +
-          " -d '{ \"title\": \"$latestMergeBranchName for dev\", \"body\": \"$prMessage\", \"head\": \"$latestMergeBranchName\", \"base\": \"dev\"," +
-          "\"draft\":\"true\"}'"
-      sh(script: curlCmd, returnStdout: true)
-    }
-
-    // switch back to main branch for further processing
-    sh(script: "set +x && cd $projectName && git checkout $currentBranchName")
-  }
-}
-
-def createAndPushTagOnMain(String projectName, String sshCredentialsId) {
-  String tagBranchName = 'main'
-
-  String projectVersion =
-      sh(returnStdout: true, script: "set +x && cd ${projectName}; ./gradlew -q printVersion").trim()
-
-  try {
-    withCredentials([
-      sshUserPrivateKey(credentialsId: sshCredentialsId, keyFileVariable: 'sshKey')
-    ]) {
-      // set tagging mail and name in git config
-      sh(script: "set +x && cd $projectName && " +
-      "git config user.email 'johannes.hiry@tu-dortmund.de' && " +
-      "git config user.name 'Johannes Hiry'", returnStdout: false)
-
-      // cleanup repo and tag it afterwards
-      sh(script:
-      "set +x && cd $projectName && " +
-      "ssh-agent bash -c \"set +x && ssh-add $sshKey; " +
-      "git branch | grep -v \"$tagBranchName\" | xargs git branch -D; " + // deletes all local branches except tagBranchName
-      "git fetch && git checkout $tagBranchName && git pull && " +
-      "git tag -m 'Release version $projectVersion.' $projectVersion && " +
-      "git push origin --tags" +
-      "\"", returnStdout: false)
-    }
-  } catch (Exception e) {
-    println "Error when creating tag on main branch! Exception: $e"
-  }
-}
-
-def deployJavaDocs(String projectName, String sshCredentialsId, String gitCheckoutUrl) {
-
-  try {
-    withCredentials([
-      sshUserPrivateKey(credentialsId: sshCredentialsId, keyFileVariable: 'sshKey')
-    ]) {
-      // set mail and name in git config
-      sh(script: "set +x && cd $projectName && " +
-      "git config user.email 'johannes.hiry@tu-dortmund.de' && " +
-      "git config user.name 'Johannes Hiry'", returnStdout: false)
-
-      // create a temporary repo in the javadocs folder and push the updated javadocs to api-docs branch
-      sh(script: "set +x && cd $projectName && " +
-      "./gradlew clean && rm -rf tmp-api-docs && mkdir tmp-api-docs && cd tmp-api-docs && " +
-      "ssh-agent bash -c \"set +x && ssh-add $sshKey; " +
-      "git init && git remote add origin $gitCheckoutUrl && " +
-      "git config user.email 'johannes.hiry@tu-dortmund.de' && " +
-      "git config user.name 'Johannes Hiry' && " +
-      "git fetch --depth=1 origin api-docs && " +
-      "git checkout api-docs && " +
-      "cd .. && ./gradlew clean javadoc && " +
-      "cp -R build/docs/javadoc/* tmp-api-docs && " +
-      "cd tmp-api-docs &&" +
-      "git add --all && git commit -m 'updated api-docs' && git push origin api-docs:api-docs" +
-      "\"",
-      returnStdout: false)
-    }
-  } catch (Exception e) {
-    println "Error when deploying javadocs! Exception: $e"
-  }
-}
-
-/* gradle */
-
-def gradle(String command, String relativeProjectDir) {
-  env.JENKINS_NODE_COOKIE = 'dontKillMe' // this is necessary for the Gradle daemon to be kept alive
-
-  // switch directory to be able to use gradle wrapper
-  sh(script: """set +x && cd $relativeProjectDir""" + ''' set +x; ./gradlew ''' + """$command""", returnStdout: true)
-}
-
-def determineSonarqubeGradleCmd(String sonarqubeProjectKey, String currentBranchName, String targetBranchName, String orgName, String projectName, String relativeGitDir) {
-  String prBaseBranch = targetBranchName == null ? "dev" : targetBranchName
-  switch (currentBranchName) {
-    case "main":
-      return "sonarqube -Dsonar.branch.name=main -Dsonar.projectKey=$sonarqubeProjectKey"
-      break
-    case "dev":
-      String[] branchVersion = gradle("-q currentVersion", relativeGitDir).toString().split('\\.')
-      Integer major = branchVersion[0].toInteger()
-      Integer minor = branchVersion[1].toInteger()
-      String projectVersion = "${major}.${minor}-SNAPSHOT"
-      return "sonarqube -Dsonar.projectVersion=${projectVersion} -Dsonar.projectKey=$sonarqubeProjectKey"
-      break
-    default:
-      String gradleCommand = "sonarqube -Dsonar.projectKey=$sonarqubeProjectKey"
-    // if this branch has a PR, the sonarqube cmd needs to be adapted
-      if (env.CHANGE_ID == null) {
-        // no PR exists
-        return gradleCommand + " -Dsonar.branch.name=${currentBranchName}"
-      } else {
-        // PR exists, adapt cmd accordingly
-        return gradleCommand + " -Dsonar.pullrequest.branch=${currentBranchName} -Dsonar.pullrequest.key=${env.CHANGE_ID} " +
-            "-Dsonar.pullrequest.base=$prBaseBranch -Dsonar.pullrequest.github.repository=${orgName}/${projectName} " +
-            "-Dsonar.pullrequest.provider=Github"
-      }
-      break
-  }
-}
-
-def determineDisplayName(String currentBranchName, String commitHash, String orgName, String projectName) {
-
-  String displayName = ""
-  if (currentBranchName == "main" || currentBranchName == "dev") {
-    // main and dev are always merge branches
-    def jsonObject = getGithubCommitJsonObj(commitHash, orgName, projectName)
-    displayName = "${jsonObject.commit.message} (${currentBuild.displayName})"
-  } else {
-    displayName = currentBranchName + " (" + currentBuild.displayName + ")"
-  }
-
-  return displayName
-}
-
-def publishReports(String relativeProjectDir) {
-  // publish test reports
-  publishHTML([allowMissing: true, alwaysLinkToLastBuild: true, escapeUnderscores: false, keepAll: true, reportDir: relativeProjectDir + '/build/reports/tests/test', reportFiles: 'index.html', reportName: "${relativeProjectDir}_java_tests_report", reportTitles: ''])
-
-  // publish pmd report for main project only
-  publishHTML([allowMissing: true, alwaysLinkToLastBuild: true, escapeUnderscores: false, keepAll: true, reportDir: relativeProjectDir + '/build/reports/pmd', reportFiles: 'main.html', reportName: "${relativeProjectDir}_pmd_report", reportTitles: ''])
-
-  // publish spotbugs report for main project only
-  publishHTML([allowMissing: true, alwaysLinkToLastBuild: true, escapeUnderscores: false, keepAll: true, reportDir: relativeProjectDir + '/build/reports/spotbugs', reportFiles: 'main.html', reportName: "${relativeProjectDir}_spotbugs_report", reportTitles: ''])
-
-  // publish scapegoat src report for main project only
-  publishHTML([allowMissing: false, alwaysLinkToLastBuild: true, escapeUnderscores: false, keepAll: true, reportDir: relativeProjectDir + '/build/reports/scapegoat/src', reportFiles: 'scapegoat.html', reportName: "${relativeProjectDir}_scapegoat_src_report", reportTitles: ''])
-
-  // publish scapegoat testsrc report for main project only
-  publishHTML([allowMissing: false, alwaysLinkToLastBuild: true, escapeUnderscores: false, keepAll: true, reportDir: relativeProjectDir + '/build/reports/scapegoat/testsrc', reportFiles: 'scapegoat.html', reportName: "${relativeProjectDir}_scapegoat_testsrc_report", reportTitles: ''])
-
-  // scoverage report dir
-  publishHTML([allowMissing: false, alwaysLinkToLastBuild: true, escapeUnderscores: false, keepAll: true, reportDir: relativeProjectDir + '/build/reports/scoverageTest', reportFiles: 'scoverage.xml', reportName: "${relativeProjectDir}_scoverage_report", reportTitles: ''])
-}
-
-def prFromFork() {
-  return env.CHANGE_FORK != null
-}
-
-/**
- * utility functions - methods that does not require node context
- */
-
-/* properties */
-
-def constantBranchesProps() {
-  properties([
-    parameters(
-    [
-      string(defaultValue: '', description: '', name: 'deploy', trim: true)
-    ]),
-    [$class: 'ThrottleJobProperty', categories: [], limitOneJobWithMatchingParams: false, maxConcurrentPerNode: 0, maxConcurrentTotal: 0, paramsToUseForLimit: '', throttleEnabled: true, throttleOption: 'project']
-  ])
-}
-
-def temporaryBranchesProps() {
-  properties(
-      [
-        pipelineTriggers([
-          issueCommentTrigger('.*!test.*')
-        ])
-      ])
-}
-
-/* git interaction */
-
-def getGithubCommitJsonObj(String commit_sha, String orgName, String repoName) {
-  def jsonObj = readJSON text: curlByCSHA(commit_sha, orgName, repoName)
-  return jsonObj
-}
-
-def curlByCSHA(String commit_sha, String orgName, String repoName) {
-
-  def curlUrl = "curl -s https://api.github.com/repos/" + orgName + "/" + repoName + "/commits/" + commit_sha
-  String jsonResponseString = sh(script: curlUrl, returnStdout: true)
-
-  return jsonResponseString
-}
-
-def getGithubPRJsonObj(String prId, String orgName, String repoName) {
-  def jsonObj = readJSON text: curlByPR(prId, orgName, repoName)
-  return jsonObj
-}
-
-def curlByPR(String prId, String orgName, String repoName) {
-  def curlUrl = "set +x && curl -s https://api.github.com/repos/" + orgName + "/" + repoName + "/pulls/" + prId
-  String jsonResponseString = sh(script: curlUrl, returnStdout: true)
-  return jsonResponseString
-}
-
-def getPRJsonObj(String orgName, String projectName, String changeId) {
-  if (changeId == null) {
-    return null
-  } else {
-    // PR exists, curl the api and retrieve target branch
-    return getGithubPRJsonObj(changeId, orgName, projectName)
-  }
-}
-
-
-def checkVersion(String branchName, String targetBranchName, String relativeGitDir,
-    String projectName,
-    String baseGitCheckoutUrl,
-    String headGitCheckoutUrl,
-    String sshCredentialsId) {
-  // get current branch type
-  // if headGitCheckoutUrl is set (= pr from fork), this branch type is always treated as a feature branch
-  String branchType = prFromFork() ? "feature" : getBranchType(branchName)
-  if (branchType == null) {
-    println "Cannot derive branch type from current branch with name '$branchName'."
-    return -1
-  }
-
-  // compare the version
-  /// save the current version string
-  String[] currentVersion = gradle("-q currentVersion", relativeGitDir).toString().split('\\.')
-
-  /// switch to the comparison branch, this is always the base git checkout url
-  gitCheckout(projectName, baseGitCheckoutUrl, targetBranchName, sshCredentialsId)
-  String[] targetBranchVersion = gradle("-q currentVersion", relativeGitDir).toString().split('\\.')
-
-  if (compareVersionParts(branchType, currentVersion, getBranchType(targetBranchName), targetBranchVersion) != 0) {
-    // comparison failed
-    return -1
-  } else {
-    // switch back to current branch. Select url depending on if this is a fork or not
-    gitCheckout(projectName, headGitCheckoutUrl, branchName, sshCredentialsId)
-    return 0
-  }
-}
-
-def compareVersionParts(String sourceBranchType, String[] sourceBranchVersion, String targetBranchType, String[] targetBranchVersion) {
-
-  switch (sourceBranchType) {
-    case "hotfix":
-      if (targetBranchType == "main") {
-        boolean major = sourceBranchVersion[0].toInteger() == targetBranchVersion[0].toInteger()
-        boolean minor = sourceBranchVersion[1].toInteger() == targetBranchVersion[1].toInteger()
-        boolean patch = (sourceBranchVersion[2].toInteger() == targetBranchVersion[2].toInteger() + 1)
-
-        if (major && minor && patch) {
-          return 0
-        } else {
-          println "Hotfix branch versioning is invalid in comparison to main branch versioning. " +
-              "Only mainBranch.patchVersion + 1 is allowed for hotfix branch!\n" +
-              "hotfixVersion: ${sourceBranchVersion[0]}.${sourceBranchVersion[1]}.${sourceBranchVersion[2]}\n" +
-              "mainVersion: ${targetBranchVersion[0]}.${targetBranchVersion[1]}.${targetBranchVersion[2]}"
-          return -1
-        }
-      } else if (targetBranchType == "dev") {
-
-        boolean major = sourceBranchVersion[0].toInteger() == targetBranchVersion[0].toInteger()
-        boolean minor = sourceBranchVersion[1].toInteger() == targetBranchVersion[1].toInteger()
-        boolean patch = (sourceBranchVersion[2].toInteger() == 0 && targetBranchVersion[2].toInteger() == 0)
-
-        if (major && minor && patch) {
-          return 0
-        } else {
-          println "Hotfix branch versioning is invalid in comparison to dev branch versioning. " +
-              "Major and minor version must be equal and patch version must be 0.\n" +
-              "hotfixVersion: ${sourceBranchVersion[0]}.${sourceBranchVersion[1]}.${sourceBranchVersion[2]}\n" +
-              "devVersion: ${targetBranchVersion[0]}.${targetBranchVersion[1]}.${targetBranchVersion[2]}"
-          return -1
-        }
-      } else {
-        // invalid branch type for hotfix merge
-        return -1
-      }
-      break
-    case "feature":
-      if (targetBranchType == "dev") {
-        // no change in semVer allowed
-        boolean major = sourceBranchVersion[0].toInteger() == targetBranchVersion[0].toInteger()
-        boolean minor = sourceBranchVersion[1].toInteger() == targetBranchVersion[1].toInteger()
-        boolean patch = (sourceBranchVersion[2].toInteger() == 0 && targetBranchVersion[2].toInteger() == 0)
-
-        if (major && minor && patch) {
-          return 0
-        } else {
-          println "Feature branch versioning differs from dev branch versioning. This is not allowed!\n" +
-              "featureVersion: ${sourceBranchVersion[0]}.${sourceBranchVersion[1]}.${sourceBranchVersion[2]}\n" +
-              "devVersion: ${targetBranchVersion[0]}.${targetBranchVersion[1]}.${targetBranchVersion[2]}"
-          return -1
-        }
-      } else {
-        // invalid branch type for feature merge
-        println "Invalid target branch type '$targetBranchType' for feature branch. Feature branches can only" +
-            "be merged into dev branch!"
-        return -1
-      }
-      break
-    case "release":
-      if (targetBranchType == "main" || targetBranchType == "dev") {
-        Integer targetMajor = targetBranchVersion[0].toInteger()
-        Integer targetMinor = targetBranchVersion[1].toInteger()
-
-        Integer sourceMajor = sourceBranchVersion[0].toInteger()
-        Integer sourceMinor = sourceBranchVersion[1].toInteger()
-
-        boolean validCheck1 = targetMajor == sourceMajor && targetMinor + 1 == sourceMinor
-        boolean validCheck2 = targetMajor + 1 == sourceMajor
-
-        // patch version always needs to be 0
-        boolean patchValid = sourceBranchVersion[2].toInteger() == 0
-
-        if ((validCheck1 || validCheck2) && patchValid) {
-          return 0
-        } else {
-          println "Release branch versioning does not fit to main branch versioning!\nA release should increase " +
-              "either major or minor version and reset patch version to 0.\n" +
-              "releaseVersion: ${sourceBranchVersion[0]}.${sourceBranchVersion[1]}.${sourceBranchVersion[2]}\n" +
-              "${targetBranchType == "main" ? "mainVersion" : "devVersion"}: ${targetBranchVersion[0]}.${targetBranchVersion[1]}.${targetBranchVersion[2]}"
-          return -1
-        }
-      } else {
-        // invalid target branch type for release merge
-        println "Merging release branch into branch type '$targetBranchType' is not supported! Realease branches" +
-            "can only be merged into main or dev branch!"
-        return -1
-      }
-    // major == major OR major == major + 1, minor == minor OR minor == minor + 1, patch == patch == 0
-      break
-    case "dev":
-    // target branch type can only be main branch
-      if (targetBranchType == "main") {
-        // only major and minor version parts need to be checked
-        Integer targetMajor = targetBranchVersion[0].toInteger()
-        Integer targetMinor = targetBranchVersion[1].toInteger()
-
-        Integer sourceMajor = sourceBranchVersion[0].toInteger()
-        Integer sourceMinor = sourceBranchVersion[1].toInteger()
-
-        boolean validCheck1 = targetMajor == sourceMajor && targetMinor + 1 == sourceMinor
-        boolean validCheck2 = targetMajor + 1 == sourceMajor
-
-        // patch version always needs to be 0
-        boolean patchValid = sourceBranchVersion[2].toInteger() == 0
-
-        if ((validCheck1 || validCheck2) && patchValid) {
-          return 0
-        } else {
-          println "Dev branch versioning does not fit to main branch versioning! Must increase either major or minor version!\n" +
-              "devVersion: ${sourceBranchVersion[0]}.${sourceBranchVersion[1]}.${sourceBranchVersion[2]}\n" +
-              "mainVersion: ${targetBranchVersion[0]}.${targetBranchVersion[1]}.${targetBranchVersion[2]}"
-          return -1
-        }
-      } else {
-        // invalid branch type for dev branch version comparison
-        println "Invalid branch type '$targetBranchType' to be compared with dev branch. Dev branch version " +
-            "can only be compared with main branch type!"
-        return -1
-      }
-      break
-    default:
-      return -1
-      break
-  }
-}
-
-def getBranchType(String branchName) {
-  def dev_pattern = "^(developer|develop|dev)\$"
-  def release_pattern = ".*rel/.*"
-  def feature_pattern = "^\\pL{2}/#\\d+.*"
-  def dependabot_pattern = "^dependabot/.*\$"
-  def hotfix_pattern = ".*hotfix/\\pL{2}/#\\d+.*"
-  def main_pattern = ".*main"
-  if (branchName =~ feature_pattern || branchName =~ dependabot_pattern) {
-    return "feature"
-  } else if (branchName =~ release_pattern) {
-    return "release"
-  } else if (branchName =~ main_pattern) {
-    return "main"
-  } else if (branchName.toLowerCase() =~ dev_pattern) {
-    return "dev"
-  } else if (branchName =~ hotfix_pattern) {
-    return "hotfix"
-  } else {
-    return null
-  }
-}
diff --git a/build.gradle b/build.gradle
index b1f482db..7b7a649f 100644
--- a/build.gradle
+++ b/build.gradle
@@ -14,7 +14,7 @@ plugins {
 }
 
 ext {
-  javaVersion = JavaVersion.VERSION_17
+  javaVersion = JavaVersion.VERSION_21
 
   scalaVersion = '3'
   scalaBinaryVersion = '3.7.4'
@@ -31,6 +31,8 @@ java {
   toolchain {
     languageVersion.set(JavaLanguageVersion.of(javaVersion.toString()))
   }
+  sourceCompatibility = javaVersion
+  targetCompatibility = javaVersion
 }
 
 group = 'com.github.ie3-institute'