How to add soap header when making a soap request using the java objects generated by wsdl

I generated client java objects using JAX-WS RI. I am trying to make a SOAP request to a web service. Service requires authentication in the header which looks like below:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
<soapenv:Header>
<xsd:authHeader>
<xsd:user>username@gmail.com</xsd:user>
<xsd:password>password1</xsd:password>
</xsd:authHeader>
</soapenv:Header>
<soapenv:Body>
<ns:searchAssetsParam>
<ns:includeSubfolders>true</ns:includeSubfolders>
<ns:resultsPage>2</ns:resultsPage>
</ns:searchAssetsParam>
</soapenv:Body>
</soapenv:Envelope>

The generated java objects have methods for calling the service, creating the objects and constructing the header. But, I am having trouble setting the header while making the call.

Here's the code that I am using:

IpsApiService service = new IpsApiService();
IpsApiPortType port = service.getIpsApiSoapPort();
SearchAssetsParam searchAssetsParam = buildSearchAssetsParam();
SearchAssetsReturn response = port.searchAssets(searchAssetsParam);

buildSearchAssetsParam() constructs the request object. I created the header object as follows:

AuthHeader header = new AuthHeader();
header.setUser("username@gmail.com");
header.setPassword("password1");

How do I set this AuthHeader to the service request?

Thanks, Venu