Passing upstream parameters to downstream builds in Jenkins

Jenkins has cool Pipeline plugin, which helps to create build pipelines, that for example, can organize and visualize deployment process. Plugin is very cool and looks great, but lacks few basic features, like passing generated parameters or variables from upstream builds to downstream.
For example, I wanted to pass SVN revision number into downstream builds.
Fortunately it is easy to do it with little hacking. Here is what I did.

1. Add Groovy plugin.
2. Add new build step Execute system Groovy script, now it is possible to hook into Jenkins internals.
3. Then just add Groovy script there:

import hudson.model.*
def thr = Thread.currentThread()
def build = thr?.executable
build.addAction(new ParametersAction(new StringParameterValue('SVN_UPSTREAM', build.getEnvVars()['SVN_REVISION'])))

What this script does it just creates new parameter and adds SVN_REVISION from environment variables there. And pipeline can pass parameters with this mechanism to downstream builds (all of them).
Easy!