Set dynamic data for requestBody - karate

Question

I am unable to read request body while running a feature file:
Details:
user.json contains:
{"userId": "", "user": { "userName": "" }}
I am setting these values to some random data generation using func:
util -> common-utilis.featurefunction() {return Java.type('util.Utilities').generateRandomString(4);}
Feature file to set up random values:
setupData.feature
Feature: Set random dataScenario: Set data* def requestBody = read('classpath:../template/user.json')
#random data generation
* set requestBody.userId = "User_ID" + "_" + randomString()
* set requestBody.user.userName = "UserName" + "_" + randomString()
set up header details in seperate feature file:
header.featureFeature: Run Check
Scenario: Run Check* url BASE_URLGiven path 'user'And header Content-Type = 'application/json'And request requestBodyWhen method post
Scenario file:
userTest.feature
Feature: As a user, I want user service to support async call
Background: Setup
* def requestBody = callonce read('../template/setupData.feature')
* print requestBody
* def result = callonce read('../header.feature')
* print result
* def response = result.response
* def responseHeaders = result.responseHeaders
Scenario: Successful response for a request
Then assert result.responseStatus == 200
What I tried so far:
I ran setupData.feature and can see system creates request body with random data successfully
I ran userTest.feature but system is displaying extra {} set
here is o/p while executing my feature file: (request body)
{"requestBody": {"userId": "User_Id_CsmY","user": {"userName": "UserName_PNKP"}}}
I can see extra {} and requestBody text
Not sure why these extra things are populated