def job = hudson.model.Hudson.instance.getJob("job")
def params = new StringParameterValue('PARAMTEST', "somestring")
def paramsAction = new ParametersAction(params)
def cause = new hudson.model.Cause.UpstreamCause(currentBuild)
def causeAction = new hudson.model.CauseAction(cause)
def scheduledJob = hudson.model.Hudson.instance.queue.schedule(job, 0, causeAction, paramsAction)

def url = scheduledJob.getFuture().waitForStart().getUrl()