WSO2 Integrator: REST API GET Request missing response body - wso2

Question

I am using WSO2 Integrator 6.6.0 to make a blocking HTTP GET to a REST API that returns a JSON response (HTTP 200 OK).
But I never see the response body inside my sequences. I am not sure what I am doing wrong, having exhausted all available documentation and other threads.
Sequence doing the call (simplified to anonymize), which logs the response afterwards:
<!-- Remove XML body as not needed for GET request -->
<payloadFactory media-type="json">
<format></format>
<args></args>
</payloadFactory>
<header name="Accept" value="application/json" scope="transport"/>
<property name="NO_ENTITY_BODY" value="true" scope="axis2" type="BOOLEAN" />
<call blocking="true">
<endpoint>
<http method="GET" uri-template="http://my-api/order-status">
</endpoint>
</call>
<property name="RESPONSE" scope="default" type="STRING" value="true"/>
<log level="full">
<property name="response-log" value="Received response"/>
<property expression="$body" name="response-body"/>
<property expression="json-eval($)" name="json-eval-body"/>
</log>
This results simply into a log line - with no response body at all!
INFO {org.apache.synapse.mediators.builtin.LogMediator} - To:
http://my-api/order-status, WSAction: urn:mediate, SOAPAction:
urn:mediate, MessageID:
ID:414d51204343494153303131202020209ca4175f28ac422e, Direction:
response, response-log = Received response, response-body =
<soapenv:Body
xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"></soapenv:Body>,
json-eval-body = {}, Payload: {}
I can see the request in my API application and I can also see what it correctly returns a response body in its logs. Also, using Postman to do the same request I receive the following JSON response with 200 OK and Content-Type appication/json:
{
"order_status": "NOT_FOUND"
}
Inside WSO2 I do not see anything! I want to be able to convert the response into XML format.
What could be wrong?

Answer 1

Before making a REST call, it is necessary to remove the headers from the main call.
Put this snippet before the call mediator:
<property name = "FORCE_HTTP_CONTENT_LENGTH" scope = "axis2" type = "STRING" value = "true" />
<property action = "remove" name = "REST_URL_POSTFIX" scope = "axis2" />
<property action = "remove" name = "TRANSPORT_HEADERS" scope = "axis2" />
As I understand it should solve.

Answer 2

Can you modify the NO_ENTITY_BODY property as follows and try this mediation again.
<property name="NO_ENTITY_BODY" action="remove" scope="axis2"/>

Answer 3

Having simplified this configuration for this question, I had missed that having the following property set in my proxy service:
<property name="OUT_ONLY" scope="default" type="STRING" value="true"/>
Means that WSO2 is ignoring the response from the API. Removing this property resolved the issue for the following config:
<header name="Accept" value="application/json" scope="transport" />
<property action="remove" name="NO_ENTITY_BODY" scope="axis2"/>
<property name="messageType" scope="axis2" type="STRING" value="application/json"/>
<call blocking="true">
<endpoint key="conf:/endpoints/FX_TRADING_API_ORDERSTATUS.xml"/>
</call>