Netbeans with JAXB Random ClassCastException ..cannot be cast to com.sun.xml.bind.v2.runtime.reflect.Accessor

I have downloaded the Soap messages from a SOAP Service and trying to mock the Soap service by returning the downloaded messages. the following code shows how I am Unmarshalling the Soap message into the required Response

    public static DataClientType unmarshallFile(String fileName) throws Exception {
    XMLInputFactory xif = XMLInputFactory.newFactory();
    XMLStreamReader xsr = xif.createXMLStreamReader(ClientSampleSoapResponseData.class.getResourceAsStream(fileName));
    xsr.nextTag(); // Advance to Envelope tag
    xsr.nextTag(); // Advance to Header
    xsr.nextTag(); // Advance to Body tag
    xsr.nextTag(); // Advance to getClientByAccountResponse
    xsr.nextTag(); // Advance to content of getClientByAccountResponse

    JAXBContext jc = JAXBContext.newInstance(GetClientByAccountResponse.class);
    Unmarshaller unmarshaller = jc.createUnmarshaller();
    JAXBElement<GetClientByAccountResponse> je = unmarshaller.unmarshal(xsr, GetClientByAccountResponse.class);

    return je.getValue().getClientDataContract();
}

However I keep getting this ClassCastExeption which happens randomly. After a number of test iterations, it begins to happen. Sometimes a clean and build fixes it but sometimes it doesn't work.

java.lang.ClassCastException: com.x.X.X.X.GetClientByAccountResponse$JaxbAccessorF_clientDataContract cannot be cast to com.sun.xml.bind.v2.runtime.reflect.Accessor
at com.sun.xml.bind.v2.runtime.reflect.opt.OptimizedAccessorFactory.instanciate(OptimizedAccessorFactory.java:188)
at com.sun.xml.bind.v2.runtime.reflect.opt.OptimizedAccessorFactory.get(OptimizedAccessorFactory.java:180)
at com.sun.xml.bind.v2.runtime.reflect.Accessor$FieldReflection.optimize(Accessor.java:256)
at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.<init>(SingleElementNodeProperty.java:90)

I have tried other online suggestions such as reverting to old jaxb versions and using endors