SOAPProxy in JBoss Enterprise SOA-P 5.3.1 does not handle WSDL imports correctly

Issue

• If there is a scenario where the WSDL exposed by a WebService imports another WSDL, it has been observed that SOAPProxy in JBoss ESB 4.11 CP1 does not handle this WSDL properly. The exception is given below for reference. However, invoking the WebService's endpoint directly does not cause any issue.

WARN  [SOAPProxy] null binding for soapaction [""]; parsing envelope to find element or operation...
ERROR [SOAPProxy] null binding for element [{http://www.xx.com/test/testInterface/schema/types}testrequest] or operation [{http://www.xx.com/test/testInterface/schema/types}testrequest] in addition to soapaction [""]
ERROR [[HttpGateway]] Servlet.service() for servlet HttpGateway threw exception
org.jboss.soa.esb.actions.ActionProcessingException: null transport for soapaction [""], element [{http://www.xx.com/test/testInterface/schema/types}testrequest], operation [{http://www.xx.com/test/testInterface/schema/types}testrequest], binding [null]
    at org.jboss.soa.esb.actions.soap.proxy.SOAPProxy.process(SOAPProxy.java:406)
    at org.jboss.soa.esb.listeners.message.ActionProcessingPipeline.processPipeline(ActionProcessingPipeline.java:649)
    at org.jboss.soa.esb.listeners.message.ActionProcessingPipeline.processPipeline(ActionProcessingPipeline.java:603)
    at org.jboss.soa.esb.listeners.message.ActionProcessingPipeline.process(ActionProcessingPipeline.java:433)
    at org.jboss.soa.esb.listeners.message.MessageAwareListener$TransactionalRunner.run(MessageAwareListener.java:550)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:662)
        ...

The earlier release of JBoss Enterprise SOA-P 5.0.2 (JBoss ESB 4.7 CP2) doesn't complain about this issue. Can you please advice what is the root cause of this problem and how to fix it?