def NuGetStore = "packages"
...
stage ('SonarQube') {
  when { expression { Settings.Analyse } }
  steps {
    script {
      retry(3) {
        bat "${Tools.NuGet.Run} install -ExcludeVersion -Source \"${Tools.Sonar.Source}\" -OutputDirectory ${NuGetStore} ${Tools.Sonar.Package}"
        Tools.Sonar.Run = new File (NuGetStore, Tools.Sonar.Run).toString()
        bat "${Tools.Sonar.Run} ${Tools.Sonar.Version}"
      }
    }
  }
}