What causes the type attribute to be specified within SOAP:BODY?

[Shinde, Uma]

 Here's a snippet of the code generated using WSDL2Java

       javax.xml.rpc.namespace.QName p0QName = new 
javax.xml.rpc.namespace.QName("http://my.com/someuri/";, "assetsetName");
        call.addParameter(p0QName, new 
javax.xml.rpc.namespace.QName("http://www.w3.org/2001/XMLSchema";, "string"), 
javax.xml.rpc.ParameterMode.IN);
        Object resp = call.invoke(new Object[] {assetsetName});

Ans here's how this looks in the SOAP request being sent -
   <assetsetName>someString</assetsetName>

What causes the type attribute to get added? I would like the request to look as 
follows:

   <assetsetName xsi:type="xsd:string">someString</assetsetName>