Re-enable and move TWR test sources to java9 source set.

Fixes: b/228587114
Change-Id: I6c61b07b74c23169b8332bddfe4af6b900aab2dd
diff --git a/src/test/examplesJava9/twraddsuppressed/TestClass.java b/src/test/examplesJava9/twraddsuppressed/TestClass.java
new file mode 100644
index 0000000..61285ce
--- /dev/null
+++ b/src/test/examplesJava9/twraddsuppressed/TestClass.java
@@ -0,0 +1,46 @@
+// Copyright (c) 2022, the R8 project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+package twraddsuppressed;
+
+import java.io.Closeable;
+
+public class TestClass {
+
+  public static class MyClosable implements Closeable {
+
+    @Override
+    public void close() {
+      throw new RuntimeException("CLOSE");
+    }
+  }
+
+  public static void foo() {
+    throw new RuntimeException("FOO");
+  }
+
+  public static void bar() {
+    // Use twr twice to have javac generate a shared $closeResource helper.
+    try (MyClosable closable = new MyClosable()) {
+      foo();
+    }
+    try (MyClosable closable = new MyClosable()) {
+      foo();
+    }
+  }
+
+  public static void main(String[] args) {
+    try {
+      bar();
+    } catch (Exception e) {
+      Throwable[] suppressed = e.getSuppressed();
+      if (suppressed.length == 0) {
+        System.out.println("NONE");
+      } else {
+        for (Throwable throwable : suppressed) {
+          System.out.println(throwable.getMessage());
+        }
+      }
+    }
+  }
+}