steps {
    parameterPoolBuilder {
        // Multiple projects can be specified to check for values.
        projects(testsString)
        // Name for the parameter.
        name('username')
        // Values for the parameter pool.
        values('qa1, qa2, qa3, qa4, qa5, qa6, qa7, qa8, qa9, qa10')
        // Check if you want the job to prefer parameter values from failed builds.
        preferError(false)
    }

    shell("mkdir -p output")
}