I am working in Generate REST API from SOAP Backend in wso2 APIM but its not working for me

Question

My resource looks like this after creating my APIM using wsdl url

<header description="SOAPAction" name="SOAPAction" scope="transport" value="urn:mediate"/>
<property name="REST_URL_POSTFIX" scope="axis2" action="remove"/>
<property expression="json-eval($.)" name="req.var."/>


<payloadFactory description="transform" media-type="xml">
  <format>
  <soapenv:Envelope xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope" xmlns:web="http://ws.apache.org/axis2">
  <soapenv:Header/>
  <soapenv:Body>
    <web:mediate xmlns:web="http://ws.apache.org/axis2"/>

  </soapenv:Body>
  </soapenv:Envelope>
  </format>
  <args>
    <arg evaluator="xml" expression="get-property('req.var.')"/>

  </args>
</payloadFactory>
<property description="messageProperty" name="messageType" scope="axis2" type="STRING" value="application/soap+xml"/>

I cannot understand this code...

When I try it gives

{ "Error": { "Message": "invalid input" } }

In log I am getting

[2022-04-21 11:40:07,448] INFO - CarbonAuthenticationUtil '[email protected] [-1234]' logged in at [2022-04-21 11:40:07,448+0530] [2022-04-21 11:40:07,760] WARN - SourceHandler STATE_DESCRIPTION = Socket Timeout occurred after accepting the request headers and the request body, INTERNAL_STATE = REQUEST_DONE, DIRECTION = REQUEST, CAUSE_OF_ERROR = Connection between the client and the EI timeouts, HTTP_URL = /SampelProxyAPI/1.0/mediate, HTTP_METHOD = POST, SOCKET_TIMEOUT = 180000, CLIENT_ADDRESS = /0:0:0:0:0:0:0:1:49255, CONNECTION http-incoming-105 [2022-04-21 11:40:08,015] INFO - LogMediator STATUS = Message dispatched to the main sequence. Invalid URL., RESOURCE = /SampelProxyAPI/1.0/mediate, HEALTH CHECK URL = /SampelProxyAPI/1.0/mediate [2022-04-21 11:48:54,087] WARN - SourceHandler I/O error: Received fatal alert: certificate_unknown