Install SonarQube Scanner plugin in jenkins
Sonar Server > Administration > Security > Users > Token > Update Tokens > Generate
Manage Jenkins > Configure System > SonarQube Servers
- Check Environment variables injection
- Add Sonarqube installations with Server authentication
  - Kind: Secret text, Secret: token generated in step 2
Configure Jenkinsfile with withSonarQubeEnv step

node {
  stage('SCM') {
    git 'https://github.com/foo/bar.git'
  }
  stage('SonarQube analysis') {
    withSonarQubeEnv() { // Will pick the global server connection you have configured
      sh './gradlew sonarqube'
    }
  }
}

Referenced from SonarScanner for Jenkins | SonarQube Docs

Sonar Server > Administration > Configuration > Webhook
- URL: http://jenkins:8080/sonarqube-webhook Secret to be empty
Update Jenkinsfile with following

pipeline {
  agent { label 'linux' }
  options {
    buildDiscarder(logRotator(numToKeepStr: '5'))
  }
  stages {
    stage('SonarQube analysis') {
    withSonarQubeEnv() { // Will pick the global server connection you have configured
      sh './gradlew sonarqube'
    }
  }
    stage("Quality Gate") {
      steps {
        timeout(time: 2, unit: 'MINUTES') {
          waitForQualityGate abortPipeline: true
        }
      }
    }
  }
}

Reference