custom-soap-fault.xml

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
   <soap:Body>
      <soap:Fault>
         <faultcode>soap:Client</faultcode>
         <faultstring>Schema validation error on message from client: "?" does not satisfy the "int" type.</faultstring>
         <detail>
            <error-reply>
               <error>Contact the administrator</error>
               <ExternalReferenceNumber>321</ExternalReferenceNumber>
               <PartnerID>123</PartnerID>
            </error-reply>
         </detail>
      </soap:Fault>
   </soap:Body>
</soap:Envelope>

FaultInterceptor.java

public class FaultInterceptor extends AbstractSoapInterceptor {

    public FaultInterceptor() {
        super(Phase.MARSHAL);
    }

    @Override
    public void handleMessage(SoapMessage message) throws Fault {
        Fault fault = (Fault) message.getContent(Exception.class);

        if (fault.getCode() != null && fault.getCode().equals("READ_VALIDATION_ERROR")) {
            Element detail = fault.getOrCreateDetail();
            Element errorDetail = detail.getOwnerDocument().createElement("error-reply");
            Element error = errorDetail.getOwnerDocument().createElement("error");
            Element extRefNumber = errorDetail.getOwnerDocument().createElement("ExternalReferenceNumber");
            Element partnerId = errorDetail.getOwnerDocument().createElement("PartnerID");

            partnerId.setTextContent("123");
            extRefNumber.setTextContent("321");
            error.setTextContent("Contact the administrator");

            errorDetail.appendChild(error);
            errorDetail.appendChild(extRefNumber);
            errorDetail.appendChild(partnerId);
            detail.appendChild(errorDetail);
        }
    }
}

invalid-soap-request.xml

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" 
                  xmlns:mule="http://ricston.com/">
   <soapenv:Header/>
   <soapenv:Body>
      <mule:add>
         <arg0>9</arg0>
         <arg1>?</arg1>
      </mule:add>
   </soapenv:Body>
</soapenv:Envelope>

mule-config-with-interceptor.xml

<flow name="proxy-service-validation">
    <http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8081"
                           path="proxy-service-validation"/>
    <cxf:proxy-service validationEnabled="true" wsdlLocation="service.wsdl" service="MyService"
                       payload="envelope" namespace="http://ricston.com/">
        <cxf:outFaultInterceptors>
            <spring:bean class="com.ricston.proxyvalidation.FaultInterceptor"/>
        </cxf:outFaultInterceptors>
    </cxf:proxy-service>
    ...
</flow>

mule-config.xml

<flow name="proxy-service-validation">
    <http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8081"
                           path="proxy-service-validation"/>
    <cxf:proxy-service validationEnabled="true" wsdlLocation="service.wsdl" service="MyService"
                       payload="envelope" namespace="http://ricston.com/"/>
    ...
</flow>

soap-fault.xml

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
   <soap:Body>
      <soap:Fault>
         <faultcode>soap:Client</faultcode>
         <faultstring>Schema validation error on message from client: "?" does not satisfy the "int" type </faultstring>
      </soap:Fault>
   </soap:Body>
</soap:Envelope>