environment variable from Jenkins

We are using Soapui plugin with Jenkins and maven. I have a requirement where we need to read the environment variables from Jenkins.

In pom.xml we have defined

<systemPropertyVariables>
<buildUrl>${BUILD_URL}</buildUrl>
</systemPropertyVariables>

And in soapui groovy script -

String JENKINS_BUILD_URL = System.getProperty("buildUrl");
log.info "Jenkins Build URL is "+JENKINS_BUILD_URL+""

But the value is coming as null.