Provide examples for jenkins integration

Setting up branch analysis and Pull request decoration is not good documented. Please add examples for the differen SCM systems.

Here my example for Bitbucket Server with Bitbucket Branch Source Plugin:
vars/sonar.groovy

def call(String params = '') {
  def sonarParams = params

  if (env.BRANCH_NAME.startsWith('PR')) {
    sonarParams += " -Dsonar.pullrequest.key=${env.CHANGE_ID} -Dsonar.pullrequest.branch=${env.CHANGE_BRANCH} -Dsonar.pullrequest.base=${env.CHANGE_TARGET}"
  } else if (env.BRANCH_NAME != 'master') {
    sonarParams += " -Dsonar.branch.target=master -Dsonar.branch.name=${env.BRANCH_NAME}"
  }

  warnError(message: 'Sonar inspection failed') {
    withSonarQubeEnv('FOO') {
      withMvn(
          pom: "./pom.xml",
          options: "${sonarParams} -Dsonar.links.ci=${env.JOB_URL} -Dsonar.userHome=${env.WORKSPACE}/.sonar",
          goal: 'sonar:sonar'
      )
    }
  }
}