Post build, Notify to Stash is not showing the Jenkins full Build URL

[✓ BUILD SUCCESS]( PLEASE SET JENKINS ROOT URL FROM GLOBAL CONFIGURATION job/XXXX/job/XXXX-pre-merge-validation/7227/)

I tested on Jenkins script console using 2 methods:

Method 1:

import jenkins.model.JenkinsLocationConfiguration

JenkinsLocationConfiguration globalConfig1 = new JenkinsLocationConfiguration();
String rootUrl = globalConfig1.getUrl();
print(" " + rootUrl)

Reponse:  Getting null as response

Method 2:

import jenkins.model.JenkinsLocationConfiguration
config = JenkinsLocationConfiguration.get();
print(" " + config.getUrl())

Response: Getting Proper Jenkins URL which was set in the Global System Configuration.

Which implies, it is not an issue with setting the URL but may be something else.