camel cxf endpoint gets a NPE after 30 seconds despite http conduit configured with large value of RecieveTimeout

Issue

We have a camel route with proxy pattern so it consumes from a camel cxf consumer endpoint and invokes out to an external service through a camel cxf producer endpoint. In case the response of the external service takes more than 30 seconds, the camel routes throws a NullPointerException even though we have a http conduit configured with ReceiveTimeout="120000":

11:38:13,472 | WARN  | qtp770349721-148 | PhaseInterceptorChain            | 74 - org.apache.cxf.cxf-core - 3.0.4.redhat-621084 | Interceptor for {http://servicemix.apache.org/samples/wsdl-first}PersonService#{http://servicemix.apache.org/samples/wsdl-first}GetPerson has thrown exception, unwinding now
java.lang.NullPointerException
    at org.apache.cxf.jaxws.interceptors.HolderOutInterceptor.handleMessage(HolderOutInterceptor.java:79)[98:org.apache.cxf.cxf-rt-frontend-jaxws:3.0.4.redhat-621084]

Here is my camel route:

<camelcxf:cxfEndpoint id="proxyEndpoint"
                    address="http://localhost:9001/person"
                    wsdlURL="META-INF/wsdl/person.wsdl"
                    serviceClass="org.apache.servicemix.samples.wsdl_first.Person"
                    serviceName="person:PersonService"
                    endpointName="person:soap"
                    xmlns:person="http://servicemix.apache.org/samples/wsdl-first" />

<camelcxf:cxfEndpoint id="invokerEndpoint"
                    address="http://localhost:8092/PersonService/"
                    wsdlURL="META-INF/wsdl/person.wsdl"
                    serviceClass="org.apache.servicemix.samples.wsdl_first.Person"
                    serviceName="person:PersonService"
                    endpointName="person:soap"
                    xmlns:person="http://servicemix.apache.org/samples/wsdl-first" />

<http-conf:conduit name="http://localhost:8092/.*">
        <http-conf:client Connection="Keep-Alive"
                      ReceiveTimeout="120000" />
    </http-conf:conduit>

<camelContext id="camel" xmlns="http://camel.apache.org/schema/blueprint">
        <route>
            <from uri="cxf:bean:proxyEndpoint"/>
            <to uri="cxf:bean:invokerEndpoint"/>
        </route>
    </camelContext>