Powershell: Invoke-WebRequest - powershell

Question

I am using the following powershell script to send xml data stored in a text file (soap.txt) to an endpoint.
$headers = New-Object "System.Collections.Generic.Dictionary[[String],[String]]"
$headers.Add("charset", 'utf-8')
$headers.Add("SOAPAction", 'nms:rtEvent#PushEvent')
Invoke-WebRequest http://localhost:8080/nl/jsp/soaprouter.jsp -Method Post -ContentType 'text/xml' -Headers $headers -InFile D:\Scripts\archive\soap.txt
Whilst the above method works fine, I wish to use the -Body param instead so that I can enrich the content but I am facing some issues, below is the code.
## Set SOAP headers
$headers = New-Object "System.Collections.Generic.Dictionary[[String],[String]]"
$headers.Add("charset", 'utf-8')
$headers.Add("SOAPAction", 'nms:rtEvent#PushEvent')
$url = "http://localhost:8080/nl/jsp/soaprouter.jsp"
$body = '<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:nms:rtEvent">
<soapenv:Header/>
<soapenv:Body>
...etc etc
</soapenv:Body>
</soapenv:Envelope>'
Invoke-WebRequest -Method Post -Uri $url -Headers $headers -Body $body -ContentType 'application/xml'
I am getting the following error
I've also tried
$body = #"
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:nms:rtEvent">
<soapenv:Header/>
<soapenv:Body>
...rest of code here asd
</soapenv:Body>
</soapenv:Envelope>
"#
Invoke-WebRequest -Method Post -Uri $url -ContentType 'text/xml' -Headers $headers -Body $body
And i get that the header must be modified using the appropiate property or method, so I append the content type also to the header but that doesn't work either, I am using powershell 3.0

Answer 1

The answer is to remove the XML indentation in the variable, is this issue documented somewhere? or is it a limitation.
$body = #"
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:nms:rtEvent">
<soapenv:Header/>
<soapenv:Body>
...rest of code here asd
</soapenv:Body>
</soapenv:Envelope>
"#