in functions_framework/lib/src/targets/json_targets.dart [120:135]
FutureOr<Response> handler(Request request) async {
final argument = await _toRequestType(request);
final context = contextForRequest(request);
final response = await _function(argument, context);
final responseJson = jsonEncode(response);
return Response.ok(
responseJson,
headers: context.responseHeaders.isEmpty
? const {contentTypeHeader: jsonContentType}
: {
contentTypeHeader: jsonContentType,
...context.responseHeaders,
},
);
}