[JExtract] Generate JNI code for classes (static methods and initializers)

Samples/JExtractJNISampleApp/Sources/MySwiftLibrary/MySwiftClass.swift

@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+public class MySwiftClass {
+  let x: Int64
+  let y: Int64
+
+  public static func method() {
+    p("Hello from static method in a class!")
+  }
+
+  public init(x: Int64, y: Int64) {
+    self.x = x
+    self.y = y
+    p("\(self)")
+  }
+
+  public init() {
+    self.x = 10
+    self.y = 5
+  }
+
+  deinit {
+    p("deinit called!")
+  }
+}

Samples/JExtractJNISampleApp/src/main/java/com/example/swift/HelloJava2SwiftJNI.java

@@ -40,6 +40,11 @@ static void examples() {
         long i = MySwiftLibrary.globalMakeInt();
         SwiftKit.trace("globalMakeInt() = " + i);
 
+        MySwiftClass.method();
+
+        MySwiftClass myClass = MySwiftClass.init(10, 5);
+        MySwiftClass myClass2 = MySwiftClass.init();
+
         System.out.println("DONE.");
     }
 }

Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaBindingsPrinting.swift

@@ -439,7 +439,7 @@ extension FFMSwift2JavaGenerator {
   }
 }
 
-extension JavaConversionStep {
+extension FFMSwift2JavaGenerator.JavaConversionStep {
   /// Whether the conversion uses SwiftArena.
   var requiresSwiftArena: Bool {
     switch self {