Multipart with quoted boundary is not parsed correctly, which is not standard compliant.

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I was using Powershell scripts to run some tests with my app embedded with uWebsockets, and found wired errors; I googled around, found this: https://github.com/PowerShell/PowerShell/issues/9241

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MultipartParser does not work with " like you say. This is not an issue in most cases but apparently Microsoft's tools rely on this.

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I had to remove quotes inside MultipartParser.prependedBoundary directly after construct;

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Really the WebSocketExtensions parsing and MultipartParser and HttpParser should be refactored to share the same parsings for things like XX="YY"; ZZ="ÅÅ" kind of parsing that is used in web protocols.