mulesoft - mongodb - restapi - id value shows extra contents - mongodb

Question

I have built a RestAPI with MongoDB using Mulesoft.
But the returned data for _id looks odd with a lot of unexpected data which are not from the DB.
How to fix this please?
Actual
[
{
"_id": {
"date": "2018-08-17T15:41:34",
"processIdentifier": 689,
"timeSecond": 1534516894,
"counter": 12813439,
"timestamp": 1534516894,
"time": 1534516894000,
"machineIdentifier": 7769240
},
"name": "Armenia",
"code": "AM"
}
]
Expected
[
{
_id: "5b76de9e768c9802b1c3848b",
name: "Armenia",
code: "AM"
}
]
Mule configuration XML
<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns:ldap="http://www.mulesoft.org/schema/mule/ldap" xmlns:dw="http://www.mulesoft.org/schema/mule/ee/dw" xmlns:metadata="http://www.mulesoft.org/schema/mule/metadata" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" xmlns:mongo="http://www.mulesoft.org/schema/mule/mongo" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:apikit="http://www.mulesoft.org/schema/mule/apikit" xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns:spring="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/apikit http://www.mulesoft.org/schema/mule/apikit/current/mule-apikit.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
http://www.mulesoft.org/schema/mule/mongo http://www.mulesoft.org/schema/mule/mongo/current/mule-mongo.xsd
http://www.mulesoft.org/schema/mule/ee/dw http://www.mulesoft.org/schema/mule/ee/dw/current/dw.xsd
http://www.mulesoft.org/schema/mule/ldap http://www.mulesoft.org/schema/mule/ldap/current/mule-ldap.xsd">
<http:listener-config name="web2-httpListenerConfig" host="0.0.0.0" port="8082" doc:name="HTTP Listener Configuration"/>
<apikit:config name="web2-config" raml="web2.raml" consoleEnabled="false" doc:name="Router"/>
<mongo:config name="Mongo_DB__Configuration" username="user1" password="123" database="mydatabase" host="mongohost" authenticationDatabase="admin" doc:name="Mongo DB: Configuration"/>
<flow name="web2-main">
<http:listener config-ref="web2-httpListenerConfig" path="/api/*" doc:name="HTTP"/>
<apikit:router config-ref="web2-config" doc:name="APIkit Router"/>
<exception-strategy ref="web2-apiKitGlobalExceptionMapping" doc:name="Reference Exception Strategy"/>
</flow>
<flow name="web2-console">
<http:listener config-ref="web2-httpListenerConfig" path="/console/*" doc:name="HTTP"/>
<apikit:console config-ref="web2-config" doc:name="APIkit Console"/>
</flow>
<flow name="get:/countries:web2-config">
<mongo:find-documents config-ref="Mongo_DB__Configuration" collection="payment" doc:name="Mongo DB"/>
<dw:transform-message doc:name="Transform Message" metadata:id="517da57f-8f6a-4b76-87fc-ea4462e438b6">
<dw:input-payload mimeType="application/java" doc:sample="sample_data\json.json"/>
<dw:set-payload><![CDATA[%dw 1.0
%output application/json
---
payload]]></dw:set-payload>
</dw:transform-message>
<set-payload value="#[payload]" doc:name="Set Payload"/>
</flow>
<apikit:mapping-exception-strategy name="web2-apiKitGlobalExceptionMapping">
<apikit:mapping statusCode="404">
<apikit:exception value="org.mule.module.apikit.exception.NotFoundException" />
<set-property propertyName="Content-Type" value="application/json" doc:name="Property"/>
<set-payload value="{ "message": "Resource not found" }" doc:name="Set Payload"/>
</apikit:mapping>
<apikit:mapping statusCode="405">
<apikit:exception value="org.mule.module.apikit.exception.MethodNotAllowedException" />
<set-property propertyName="Content-Type" value="application/json" doc:name="Property"/>
<set-payload value="{ "message": "Method not allowed" }" doc:name="Set Payload"/>
</apikit:mapping>
<apikit:mapping statusCode="415">
<apikit:exception value="org.mule.module.apikit.exception.UnsupportedMediaTypeException" />
<set-property propertyName="Content-Type" value="application/json" doc:name="Property"/>
<set-payload value="{ "message": "Unsupported media type" }" doc:name="Set Payload"/>
</apikit:mapping>
<apikit:mapping statusCode="406">
<apikit:exception value="org.mule.module.apikit.exception.NotAcceptableException" />
<set-property propertyName="Content-Type" value="application/json" doc:name="Property"/>
<set-payload value="{ "message": "Not acceptable" }" doc:name="Set Payload"/>
</apikit:mapping>
<apikit:mapping statusCode="400">
<apikit:exception value="org.mule.module.apikit.exception.BadRequestException" />
<set-property propertyName="Content-Type" value="application/json" doc:name="Property"/>
<set-payload value="{ "message": "Bad request" }" doc:name="Set Payload"/>
</apikit:mapping>
</apikit:mapping-exception-strategy>
</mule>