// Get ELID from system property
var elidProperty = gs.getProperty('wf.change.tcm.vendor.certification.users');

// Default name fallback
var username = '';

if (elidProperty) {
// Process comma-separated values to remove spaces
var idList = elidProperty.split(',').map(function(id) {
return id.trim();
}).join(',');

var userGR = new GlideRecord('sys_user');

// Construct an explicit Encoded Query string using the IN operator
// This translates to: (u_elid IN idList OR user_name IN idList) AND active=true
var queryString = "u_elidIN" + idList + "^ORuser_nameIN" + idList + "^active=true";

userGR.addEncodedQuery(queryString);
userGR.query();

if (userGR.next()) {
username = userGR.getValue('name'); // Safeguards field reference
}
}

// Build message content
var emailContent = '';
emailContent += '<br/>';

// Execute clean ternary string concatenation
var displayName = username ? username : '';
emailContent += '<p>Hi ' + displayName + ',</p>';

emailContent += '<p>As the manager of a group with access to the Vendor Change mod review and attestation.</p>';
// ... rest of your html code ...

template.print(emailContent);