AddAProperty.groovy

import org.jenkinsci.plugins.envinject.EnvInjectJobProperty
import org.jenkinsci.plugins.envinject.EnvInjectJobPropertyInfo

node('master') {
    script {
        echo 'Hello World'
        echo "$JOB_NAME"
        echo "$perform"
        persistInfo();
    }
}

def persistInfo(){

    def jenkins = Jenkins.instance
    def jobA = jenkins.getItemByFullName("$JOB_NAME")
    def prop2 = jobA.getProperty(org.jenkinsci.plugins.envinject.EnvInjectJobProperty);
    def con = prop2.getInfo().getPropertiesContent();

    def orig = []
    def str = ""
    for(e in con.split(System.getProperty("line.separator"))) {
        if (!e.contains("UPDATED_DOCKER_IMAGES")) {
            str = str + e + System.getProperty("line.separator")
        }
    }
    str = str + "UPDATED_DOCKER_IMAGES=wso2apim-2.6.0"
    
    def prop = new EnvInjectJobPropertyInfo("", str , "", "", "", false)

    def propNew = new org.jenkinsci.plugins.envinject.EnvInjectJobProperty(prop)
    propNew.setOn(true)
    propNew.setKeepBuildVariables(true)
    propNew.setKeepJenkinsSystemVariables(true)
    jobA.addProperty(propNew)

    jobA.save();
}