Post checkmarx scan weblink on the Jenkins Build status page

Question

After a build completes, on the status page I can see details like started by user, this run spent, git commits etc. How do i add something to this page after build finishes. I want to capture a checkmarx scan result web link and add that to this status page.

I want to do this as part of my checkmarx stage after the scan runs or at the end with the post build actions.

I prefer not to install any custom plugins due to organizational restrictions

I tried the following but it didnt work:

// Groovy Postbuild Script
import hudson.model.*

def build = manager.build
def customMessage = "Custom message: " // my checkmarx link here

def changeSet = build.changeSet
def changes = changeSet.getItems().collect {
    "${it.author.fullName}: ${it.msg}"
}.join('\n')

def newContent = """
    <div>
        <h3>Custom Information:</h3>
        <p>${customMessage}</p>
        <h3>Changes:</h3>
        <pre>${changes}</pre>
    </div>
"""

def action = new ParametersAction([
    new StringParameterValue('CustomInformation', newContent)
])

build.addAction(action)

Any help in this regard is much appreciated