Generates Dart built_value classes from given JSON String.
Examples:
json2builtvalue -h
json2builtvalue -n todo -i todo.json -o todo.dart
echo '{
"userId": 1,
"id": 1,
"title": "delectus aut autem",
"completed": false
}' | dart bin/main.dart -n todo
Based on json2builtvalue