Error when trying to wrap an instance of JAXBElement

I have the following code,

 JAXBContext jc = JAXBContext.newInstance(TestResults.class);
                    Marshaller m = jc.createMarshaller();
                    m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); 
                    OutputStream os = new FileOutputStream( "nosferatu.xml" );
                    TestResults tr = new TestResults();
                    tr.setUuid(new JAXBElement<String>(new QName("uuid"),String.class, "uuidcontent"));
                    //ObjectFactory objectFactory = new ObjectFactory();
                    m.marshal(new JAXBElement<TestResults>(new QName("uri","local"),TestResults.class,new TestResults()), System.out);

in which I am trying to wrap the Java String Class as a jaxb Element, since if I do not I get the

unable to marshal type “java.lang.String” error.

However when I try wrap the java.lang.string in a jaxb element, I get the following error

The method setUuid(String) in the type TestResults is not applicable for the arguments (JAXBElement<String>)

The setUuid method looks as follows

public void setUuid(java.lang.String value) {
    this.uuid = value;
}

Why is is this error happening, and how can I fix this error?