Custom SOAP header

Greetings!

Hopefully someone has an answer on this, I cannot find any example or understand from the documentation how to acheive this.

I have a SOAP header subclass

Class AddressType Extends %SOAP.Header
{

Parameter ELEMENTQUALIFIED = 1;

Parameter MAXLEN;

Parameter NAMESPACE = "urn:registry:1";

Parameter XMLNAME = "urn:LogicalAddress";

}

In my  %SOAP.WebClient I use it like this:
set customHeader = ##class(AddressType).%New()
do ..HeadersOut.SetAt(customHeader,"AddressType")

Which results in
...
<SOAP-ENV:Header>
<urn:LogicalAddress xmlns="urn:registry:1" xmlns:hdr="urn:registry:1"></urn:LogicalAddress>
</SOAP-ENV:Header>

But how do I set a value within this tag? So I get the result to look like this
<urn:LogicalAddress xmlns="urn:registry:1" xmlns:hdr="urn:registry:1">Elmstreet 12</urn:LogicalAddress>

Best regards,

Magnus