Mono WCF MTOM Encoding Omits Quotes in Content-Type Header, Breaks Strict SOAP Servers #21842

Hello. I’m encountering a discrepancy between Mono and .NET Framework when using WCF with MTOM encoding for a SOAP API. The issue boils down to Mono neglecting to wrap the type=application/xop+xml portion of the Content-Type header in quotation marks, causing a 415 Unsupported Media Type error on strict servers. .NET Framework does this correctly [ON WINDOWS], and the server expects quotes, as per SOAP/MTOM standards.
System.Net.WebException: There was an error on processing web request: Status code 415(UnsupportedMediaType): Cannot process the message because the content type 'multipart/related; type=application/xop+xml' was not the expected type 'multipart/related; type="application/xop+xml"'.
Is this intentional behavior or is it a bug?

The code that strips the quotes is found here:

mono/mcs/class/System.ServiceModel/System.ServiceModel.Channels/ContentType.cs

Thanks!