Create XML element without closing tag

I have this nested golang struct:

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<!-- language: lang-go -->

// TierRequest is the outer most XML envelope of soap request
type TierRequest struct {
	XMLName   xml.Name `xml:"soapenv:Envelope"`
	NsEnv     string   `xml:"xmlns:soapenv,attr"`
	NsType    string   `xml:"xmlns:typ,attr"`
	Header    string   `xml:"soapenv:Header"`

// TierBody is an emtpy container with the GetCollectorProfile struct
type TierBody struct {
	GetCollectorProfiles GetCollectorProfile `Collectorxml:"typ:GetCollectorProfileRequest"`
}

// GetCollectorProfile struct has the context and collector number
type GetCollectorProfile struct {
	Contexts CollectorContext `xml:"typ:Context"`
	Number   int              `xml:"typ:CollectorNumber"`
}

// CollectorContext contanins a few variables as attributes
type CollectorContext struct {
	Channel  string `xml:"Channel,attr"`
	Source   string `xml:"Source,attr"`
	Language string `xml:"LanguageCode,attr"`
}

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When I initialize it with values and marshal with encoding/xml it comes to look like this:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
                  xmlns:typ="http:/www.yahoo.com/tp/ets/2008/04/01/collector/types">
  <soapenv:Header></soapenv:Header>
  <soapenv:Body>
    <GetCollectorProfiles>
      <typ:Context Channel="WEB" Source="WEB" LanguageCode="en-CA"></typ:Context>
      <typ:CollectorNumber>50000</typ:CollectorNumber>
    </GetCollectorProfiles>
  </soapenv:Body>
</soapenv:Envelope>

How I can get rid of the closing tags for soapenv:Header and typ:Context, so it just looks like <soapenv:Header/>?

There is no difference at the XML level between an element with no content and an end-tag:

<soapenv:Header></soapenv:Header>

and an empty element tag:

<soapenv:Header/>

To control which form is used, you'd have to treat the data as text rather than as XML, but better not to worry about a difference that makes no difference.

[Added for completeness]

...other than an obscure and antiquated recommendation

> For interoperability, the empty-element tag should be used, and should
> only be used, for elements which are declared EMPTY.

regarding interoperability with SGML:

> for interoperability
>
> [Definition: Marks a sentence describing a non-binding recommendation
> included to increase the chances that XML documents can be processed
> by the existing installed base of SGML processors which predate the
> WebSGML Adaptations Annex to ISO 8879.]