src/vs/base/common/mime.ts/toTextMimeAssociationItem
function toTextMimeAssociationItem(association: ITextMimeAssociation): ITextMimeAssociationItem {
	return {
		id: association.id,
		mime: association.mime,
		filename: association.filename,
		extension: association.extension,
		filepattern: association.filepattern,
		firstline: association.firstline,
		userConfigured: association.userConfigured,
		filenameLowercase: association.filename ? association.filename.toLowerCase() : undefined,
		extensionLowercase: association.extension ? association.extension.toLowerCase() : undefined,
		filepatternLowercase: association.filepattern ? association.filepattern.toLowerCase() : undefined,
		filepatternOnPath: association.filepattern ? association.filepattern.indexOf(posix.sep) >= 0 : false
	};
}