fastjson - Java library that can be used to convert Java Objects into their JSON representation.
It can also be used to convert a JSON string to an equivalent Java object. Fastjson can work with arbitrary Java objects including pre-existing objects that you do not have source-code of.
ProGuard rules for fastjson
ProGuard removes classes, methods in the shrinking phase. ProGuard obfuscates the remaining classes, fields, and methods with short names. Add the next ProGuard-style specification for your proguard-rules.pro file.
-dontwarn com.alibaba.fastjson.** -keepattributes Signature -keepattributes *Annotation*
For more information about fastjson please see the website.