HTTP 400 bad request correct body

[todomary]

Hi, I'm trying to perform a simple HTTP task and this is my resultant xml file:

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:flowable="http://flowable.org/bpmn" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlnsmgdc="http://www.omg.org/spec/DD/20100524/DC" xmlnsmgdi="http://www.omg.org/spec/DD/20100524/DI" typeLanguage="http://www.w3.org/2001/XMLSchema" expressionLanguage="http://www.w3.org/1999/XPath" targetNamespace="http://www.flowable.org/processdef">
<process id="Login" name="Login" isExecutable="true">
<startEvent id="startEvent1"></startEvent>
<serviceTask id="LoginTask" flowable:type="http">
<extensionElements>
<flowable:field name="requestMethod">
<flowable:string><![CDATA[POST]]></flowable:string>
</flowable:field>
<flowable:field name="requestUrl">
<flowable:string><![CDATA[https://reqres.in/api/login]]></flowable:string>
</flowable:field>
<flowable:field name="requestBody">
<flowable:string><![CDATA[{"email": "peter@klaven" , "password" : "cityslicka"}]]></flowable:string>
</flowable:field>
<flowable:field name="failStatusCodes">
<flowable:string><![CDATA[400]]></flowable:string>
</flowable:field>
</extensionElements>
</serviceTask>
<sequenceFlow id="sid-36A665CF-4FA6-4849-80F2-7FF8EAAD3A49" sourceRef="startEvent1" targetRef="LoginTask"></sequenceFlow>
<endEvent id="sid-CA6A51E8-3EA5-4E1E-B580-5F8E9078B50D"></endEvent>
<sequenceFlow id="sid-62654832-D11C-4B49-AE8D-E95BDF435AAF" sourceRef="LoginTask" targetRef="sid-CA6A51E8-3EA5-4E1E-B580-5F8E9078B50D"></sequenceFlow>
</process>

</definitions>

email and password are correct, in fact if I perform a POST on Postman with these values it works. But when I run an instance it gives me HTTP 400 error. Any idea why?