Multiple attributes to a single attribute in SAML response when Auth0 is the SAML IdP

rule.js

function (user, context, callback) { 

  // Execute the rule only for the required Apps's client ID
  var samlIdpClientId = 'LYkMiVolEzhDzaTQJPg6mRI468blVFU4';
  if (context.clientID !== samlIdpClientId) {
    return callback(null, user, context);
  }
  
  user.tmpMemberOf = "";
  function appendMember(memberOf) {
    user.tmpMemberOf += memberOf + ":";
  }

  if (user.app_metadata && user.app_metadata.memberOf) {
    user.app_metadata.memberOf.forEach(appendMember);
  }

  context.samlConfiguration.mappings = {
     "userMemberOf": "tmpMemberOf"
  };

  callback(null, user, context);
}

sample_user_profile.json

{
    "email": "johndough@gmail.com",
    "email_verified": false,
    "updated_at": "2021-01-26T10:23:02.889Z",
    "user_id": "auth0|5bb836bb44a3697cd1f26db8",
    "nickname": "johndough",
    "identities": [
        {
            "user_id": "5bb836bb44a3697cd1f26db8",
            "provider": "auth0",
            "connection": "Username-Password-Authentication",
            "isSocial": false
        }
    ],
    "created_at": "2018-10-06T04:14:51.920Z",
    "name": "johndough@gmail.com",
    "user_metadata": {},
    "last_password_reset": "2019-10-11T13:39:00.517Z",
    "app_metadata": {
        "memberOf": [
            "env_A",
            "env_B"
        ]
    },
    "last_ip": "31.142.76.23",
    "last_login": "2021-01-26T10:23:02.889Z",
    "logins_count": 122,
    "blocked_for": [],
    "guardian_authenticators": []
}