Remove ns2 as default namespace prefix

All you need 2 do is when you open a new package select create package info in the package info add the following annotation or change it as needed

@javax.xml.bind.annotation.XmlSchema(namespace = "http://www.sitemaps.org/schemas/sitemap/0.9", elementFormDefault = javax.xml.bind.annotation.XmlNsForm.QUALIFIED, xmlns = { @javax.xml.bind.annotation.XmlNs(namespaceURI = "http://www.sitemaps.org/schemas/sitemap/0.9", prefix = "") })

This will remove the ns2 prefix

Most likely you have multiple namespaces in the response. This will use the default convention of creating ns# namespace prefixes and one of them becomes the xmlns without a prefix. If you want to control this you can do the following:

NamespacePrefixMapper mapper = new NamespacePrefixMapper() {
        public String getPreferredPrefix(String namespaceUri, String suggestion, boolean requirePrefix) {
            if ("http://namespace".equals(namespaceUri) && !requirePrefix)
                return "";
            return "ns";
        }
    };
    marshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", mapper);
    marshaller.mashal....

This will set the http://namespace as the default xmlns always and use ns# for all other namespaces when marshalling. You can also give them more descriptive prefixes if you want.

Beginning from JDK6u18 the NamespacePrefixMapper technique is not used anymore.