How to add blank namespace in java using javax.xml.bind.annotation

Question

I'm new to SOAP service, this is my output and java class detail.

How to add the blank xmlns in sub level class?

Out-Put Request:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<sendEmail xmlns="http://ws.cns.channel.sendnotification.sdfsfds.com/">
    <EmailNotificationRequest>
        <requestHeader>
            <channel>fsdfs</channel>
            <subChannel>sdfds</subChannel>
            <systemName>sdfsd</systemName>
            <applicationName>dsfs</applicationName>
        </requestHeader>
    </EmailNotificationRequest>
</sendEmail>

Package Class

    @javax.xml.bind.annotation.XmlSchema(namespace = "http://ws.cns.channel.sendnotification.sdfsfds.com/",
        elementFormDefault = XmlNsForm.QUALIFIED
    )
    package com.etisalat.sendnotification.channel.cns.ws;

    import javax.xml.bind.annotation.XmlNsForm;

Request Header Class

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "requestHeader", propOrder = {
    "channel",
    "subChannel",
    "agentID",
    "systemName",
    "applicationName",
    "hostID",
    "requestDate"
})

public class RequestHeader {
    @XmlElement(required = true)
    protected String channel;
    protected String subChannel;
    protected String agentID;
    @XmlElement(required = true)
    protected String systemName;
    protected String applicationName;
}

Required Input Request

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<sendEmail xmlns="http://ws.cns.channel.sendnotification.sdfsfds.com/">
    <EmailNotificationRequest>
        <requestHeader xmlns="">
            <channel>fsdfs</channel>
            <subChannel>sdfds</subChannel>
            <systemName>sdfsd</systemName>
            <applicationName>dsfs</applicationName>
        </requestHeader>
    </EmailNotificationRequest>
</sendEmail>