JSON formatter/builders don't support all the data types defined in the JSON spec

[s3valkov]

JSON mapped attributes with values of non string data types produce an error when the builder attempts to parse the stream. The following have been observed to fail when specified as values:

1 numeric (with no quotes)
2 boolean (with no quotes)
3 a subset of escaped characters inside a quoted string (e.g.'\b' backspace ascii x08)
4 null

These are all legal values in the JSON spec. http://www.ietf.org/rfc/rfc4627.txt You can use this as a guideline for what to verify.