fix warnings.

lib/src/crypto/protected_salt_generator.dart

@@ -7,13 +7,15 @@ import 'package:pointycastle/export.dart';
 class ProtectedSaltGenerator {
   factory ProtectedSaltGenerator(Uint8List key) {
     final hash = sha256.convert(key).bytes as Uint8List;
-    final cipher = Salsa20Engine()..init(false, ParametersWithIV(KeyParameter(hash), SalsaNonce));
+    final cipher = Salsa20Engine()
+      ..init(false, ParametersWithIV(KeyParameter(hash), salsaNonce));
     return ProtectedSaltGenerator._(cipher);
   }
 
   ProtectedSaltGenerator._(this._cipher);
 
-  static final SalsaNonce = Uint8List.fromList([0xE8, 0x30, 0x09, 0x4B, 0x97, 0x20, 0x5D, 0x2A]);
+  static final salsaNonce =
+      Uint8List.fromList([0xE8, 0x30, 0x09, 0x4B, 0x97, 0x20, 0x5D, 0x2A]);
   final StreamCipher _cipher;
 
   String decryptBase64(String protectedValue) {

lib/src/crypto/protected_value.dart

@@ -73,6 +73,11 @@ class ProtectedValue implements StringValue {
   bool operator ==(dynamic other) =>
       other is ProtectedValue && other.getText() == getText();
 
+  int _hashCodeCached;
+
+  @override
+  int get hashCode => _hashCodeCached ??= getText().hashCode;
+
   @override
   String toString() {
     return 'ProtectedValue{${base64.encode(hash)}}';

lib/src/kdbx_object.dart

@@ -11,6 +11,7 @@ import 'package:uuid/uuid.dart';
 import 'package:uuid/uuid_util.dart';
 import 'package:xml/xml.dart';
 
+// ignore: unused_element
 final _logger = Logger('kdbx.kdbx_object');
 
 class ChangeEvent<T> {