👌 Remove redundant credentials in authenticator

Author: Gustl22

lib/src/auth/auth.dart

@@ -17,11 +17,12 @@ abstract class PostgresAuthenticator {
   void onMessage(AuthenticationMessage message);
 }
 
-PostgresAuthenticator createAuthenticator(PostgreSQLConnection connection, UsernamePasswordCredential credentials) {
+PostgresAuthenticator createAuthenticator(PostgreSQLConnection connection) {
   switch (connection.authenticationScheme) {
     case AuthenticationScheme.MD5:
-      return MD5Authenticator(connection, credentials);
+      return MD5Authenticator(connection);
     case AuthenticationScheme.SCRAM_SHA_256:
+      final credentials = UsernamePasswordCredential(username: connection.username, password: connection.password);
       return PostgresSaslAuthenticator(connection, ScramAuthenticator('SCRAM-SHA-256', sha256, credentials));
     default:
       throw PostgreSQLException("Authenticator wasn't specified");

lib/src/auth/md5_authenticator.dart

@@ -1,6 +1,5 @@
 import 'package:buffer/buffer.dart';
 import 'package:crypto/crypto.dart';
-import 'package:sasl_scram/sasl_scram.dart';
 
 import '../../postgres.dart';
 import '../client_messages.dart';
@@ -11,9 +10,7 @@ import 'auth.dart';
 class MD5Authenticator extends PostgresAuthenticator {
   static final String name = 'MD5';
 
-  final UsernamePasswordCredential credentials;
-
-  MD5Authenticator(PostgreSQLConnection connection, this.credentials) : super(connection);
+  MD5Authenticator(PostgreSQLConnection connection) : super(connection);
 
   @override
   void onMessage(AuthenticationMessage message) {

lib/src/connection_fsm.dart

@@ -113,9 +113,7 @@ class _PostgreSQLConnectionStateAuthenticating
           continue authInit;
         authInit:
         case AuthenticationMessage.KindSASL:
-          final credential = UsernamePasswordCredential(
-              username: connection!.username, password: connection!.password);
-          _authenticator = createAuthenticator(connection!, credential);
+          _authenticator = createAuthenticator(connection!);
           continue authMsg;
         authMsg:
         case AuthenticationMessage.KindSASLContinue: