External APIs - Merchant, Budget, Deployment, Yahoo API throws exception for Media/type application/xml

1.Send SOAP request for Merchant API as media/type: application/xml

<?xml version="1.0" encoding="utf-8"?>
<merchant>
<customerId>TestMediaType</customerId>
</merchant>

2.Observe the response

Actual result:

HTTP/1.1 400 Bad Request
Server: Apache-Coyote/1.1
Date: Tue, 03 May 2016 14:29:57 GMT
Content-Type: text/plain;charset=UTF-8
Transfer-Encoding: chunked
Connection: close

JAXBException occurred : unexpected element (uri:"", local:"merchant"). Expected elements are <

merchant>. unexpected element (uri:"", local:"merchant"). Expected elements are <

merchant>.

Note : Post/PUT method is having this issue for other APIs - "Budget","DeploymentAPI" and "Yahoo Credentials "