Merge pull request jeroentrappers#6 from flawnn/null-safety

sdk: Migrate to null-safety & uprev to minimum SDK Version 2.12

Author: jeroentrappers

lib/flutter_bcrypt.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/services.dart';
 import 'package:flutter/foundation.dart';
 
@@ -9,25 +11,25 @@ class FlutterBcrypt {
   /// Salt must be a string in Modular Crypt Format with $ separators
   /// for example r'$2b$06$C6UzMDM.H6dfI/f/IKxGhu'
   static Future<String> hashPw(
-          {@required String password, @required String salt}) async =>
-      await _channel
-          .invokeMethod('hashPw', {'password': password, 'salt': salt});
+          {required String password, required String salt}) async =>
+      await (_channel
+          .invokeMethod('hashPw', {'password': password, 'salt': salt}));
 
   /// Generate a 16 byte salt with 6 rounds of cost in Modular Crypt Format.
   static Future<String> salt() async =>
-      await _channel.invokeMethod('salt', {'rounds': 6});
+      await (_channel.invokeMethod('salt', {'rounds': 6}));
 
   /// Generate a salt with a given cost. Cost must be between 4 and 31.
-  static Future<String> saltWithRounds({@required int rounds}) async =>
-      await _channel.invokeMethod('saltWithRounds', {'rounds': rounds});
+  static Future<String> saltWithRounds({required int rounds}) async =>
+      await (_channel.invokeMethod('saltWithRounds', {'rounds': rounds}));
 
   /// Verify if the given password matches the given hash.
   /// Password must be a plain UTF-8 compatible String
   /// Hash must be provided in Modular Crypt Format. Eg.
   /// $2y$06$doGnefu9cbLkJTn8sef7U.dynHJFe5hS6xp7vLWb2Zu7e8cOuMVmS
   /// This includes the version, complexity and 16 bytes of salt.
   static Future<bool> verify(
-          {@required String password, @required String hash}) async =>
-      await _channel
-          .invokeMethod('verify', {'password': password, 'hash': hash});
+          {required String password, required String hash}) async =>
+      await (_channel
+          .invokeMethod('verify', {'password': password, 'hash': hash}));
 }

pubspec.yaml

@@ -5,7 +5,7 @@ author: Jeroen Trappers <jeroen@appmire.be>
 homepage: https://github.com/jeroentrappers/flutter_bcrypt
 
 environment:
-  sdk: ">=2.1.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
   flutter: