GetBuildnumber of started downstrem Job groovy

[Sven Finsterwalder]

Hello,

i try to get the buildnumber of a started downstream Job with groovy.
Currently i got this:

def deploymentJob = 
Jenkins.getInstance().getItemByFullName('deployment-universal-automatic-2.2')
println(deploymentJob.getDownstreamProjects())

  List<AbstractProject> childs = deploymentJob.getDownstreamProjects()
  for (Iterator<AbstractProject> iterator = childs.iterator(); 
iterator.hasNext();) {
            AbstractProject project = iterator.next();
            println(project.getFullName());
        }
  
How can i now get the buildnumber of the DownstreamJob?
I have read the 
documentation<http://javadoc.jenkins-ci.org/hudson/model/AbstractProject.html>but
 i can not find a way to do it, please help me.

Thanks!