[jnigen] Override JObject's toString with appropriate Java's toString (https://github.com/dart-lang/jnigen/issues/337)

* add toString
* remove extra hashCode and == as JObject already has it

pkgs/jni/lib/src/jobject.dart

diff --git a/pkgs/jni/lib/src/jobject.dart b/pkgs/jni/lib/src/jobject.dart
index 5de5bbd..26df6be 100644
--- a/pkgs/jni/lib/src/jobject.dart
+++ b/pkgs/jni/lib/src/jobject.dart
@@ -342,6 +342,15 @@
     return Jni.accessors.callMethodWithArgs(reference, _equalsId,
         JniCallType.booleanType, [other.reference]).boolean;
   }
+
+  static final _toStringId = Jni.accessors.getMethodIDOf(
+      _objectClass.reference, r"toString", r"()Ljava/lang/String;");
+  @override
+  String toString() {
+    return JString.fromRef(Jni.accessors.callMethodWithArgs(
+            reference, _toStringId, JniCallType.objectType, []).object)
+        .toDartString(deleteOriginal: true);
+  }
 }
 
 /// A high level wrapper over a JNI class reference.

pkgs/jni/lib/src/util/jlist.dart

diff --git a/pkgs/jni/lib/src/util/jlist.dart b/pkgs/jni/lib/src/util/jlist.dart
index eac7f20..8087af9 100644
--- a/pkgs/jni/lib/src/util/jlist.dart
+++ b/pkgs/jni/lib/src/util/jlist.dart
@@ -267,21 +267,6 @@
   JSet<$E> toSet() {
     return toJSet(E);
   }
-
-  static final _hashCodeId =
-      Jni.accessors.getMethodIDOf(_class.reference, r"hashCode", r"()I");
-  @override
-  int get hashCode => Jni.accessors.callMethodWithArgs(
-      reference, _hashCodeId, JniCallType.intType, []).integer;
-
-  static final _equalsId = Jni.accessors
-      .getMethodIDOf(_class.reference, r"equals", r"(Ljava/lang/Object;)Z");
-  @override
-  bool operator ==(Object other) {
-    if (other is! JObject) return false;
-    return Jni.accessors.callMethodWithArgs(reference, _equalsId,
-        JniCallType.booleanType, [other.reference]).boolean;
-  }
 }
 
 extension ToJavaList<E extends JObject> on Iterable<E> {

pkgs/jni/lib/src/util/jset.dart

diff --git a/pkgs/jni/lib/src/util/jset.dart b/pkgs/jni/lib/src/util/jset.dart
index 5300107..367c121 100644
--- a/pkgs/jni/lib/src/util/jset.dart
+++ b/pkgs/jni/lib/src/util/jset.dart
@@ -190,23 +190,6 @@
     return super.retainAll(elements);
   }
 
-  static final _hashCodeId =
-      Jni.accessors.getMethodIDOf(_class.reference, r"hashCode", r"()I");
-  @override
-  int get hashCode => Jni.accessors.callMethodWithArgs(
-      reference, _hashCodeId, JniCallType.intType, []).integer;
-
-  static final _equalsId = Jni.accessors
-      .getMethodIDOf(_class.reference, r"equals", r"(Ljava/lang/Object;)Z");
-  @override
-  bool operator ==(Object other) {
-    if (other is! JObject) {
-      return false;
-    }
-    return Jni.accessors.callMethodWithArgs(reference, _equalsId,
-        JniCallType.booleanType, [other.reference]).boolean;
-  }
-
   @override
   $E? lookup(Object? element) {
     if (contains(element)) return element as $E;

pkgs/jni/test/jstring_test.dart

diff --git a/pkgs/jni/test/jstring_test.dart b/pkgs/jni/test/jstring_test.dart
index 1bc6436..210c91d 100644
--- a/pkgs/jni/test/jstring_test.dart
+++ b/pkgs/jni/test/jstring_test.dart
@@ -43,4 +43,9 @@
       testStringBackAndForth('');
     });
   });
+
+  testRunner('Inherited toString', () {
+    final s = 'hello'.toJString();
+    expect(s.toString(), 'hello');
+  });
 }