JSON batch body encoding for "text" content types may cause conversion errors or data loss

Possibility: only encode "text" content as a JSON string if charset=utf-8 or charset=us-ascii  is explicitly present or the defined default of the "text" sub-type, which is the case for text/plain . Otherwise encode as a string in base64url format. This proposal isn't backwards compatible with the current spec in all cases, we need to compile a list of "text" sub-types and their defined default charset to see where this might cause problems. On the other hand the current spec doesn't give instructions for encoding charsets other than UTF-8 and its true subsets as JSON strings, so a recipient of text/<something>;charset=iso-8859-16  now does not really know how to decode the stream value. Change fourth paragraph of 9 Stream Property to (inserted text in green ) If the actual stream data is included inline, the control information mediaContentType MUST be present to indicate how the included stream property value is represented. Stream property values of media type application/json or one of its subtypes, optionally with format parameters, are represented as native JSON. Values of top-level type text with an explicit or default charset of utf-8 or us-ascii , for example text/plain , are represented as a string, with JSON string escaping rules applied. Included stream data of other media types is represented as a base64url-encoded string value, see [RFC4648] , section 5.