Parsing, validation of formDef.json in ODK Survey

Hi all

I am new to ODK and i do apologize if some of these questions are
elementary. Here is my understanding based on github, wikis etc.

Here is my question. ODK Collect used Javarosa code to parse, validate XML
in the app. What does ODK Survey use to parse, validate JSON ? I am looking
in ODK Survey, androidcommon, androidlibrary code bases. I will continue
digging into the code, but would appreciate some pointers.