The AvroAsTextInput format generates a record containing
[omitted] , "someName": NaN}
A json parser chokes on that and it is not legal JSON AFAIK. In related issues
AVRO-972 and AVRO-1290 it is resolved, for lack of a better option, to map the value NaN to the string "NaN", which needs to be quoted in JSON. Our parser can handle that with no modifications, Java will parse such a string to the correct value using standard libraries.