Add attemptJava5516 - a non-deterministic reproducer

JAVA-5516

driver-core/src/test/functional/com/mongodb/internal/operation/AsyncCommandBatchCursorFunctionalTest.java

@@ -45,6 +45,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ForkJoinPool;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Collectors;
@@ -299,6 +300,24 @@ void testLimitWithGetMore() {
         assertTrue(cursor.isClosed());
     }
 
+    @Test
+    void attemptJava5516() {
+        BsonDocument commandResult = executeFindCommand(5, 2);
+        cursor = new AsyncCommandBatchCursor<>(commandResult, 2, 0, DOCUMENT_DECODER,
+                                               null, connectionSource, connection);
+        assertNotNull(cursorNext());
+        // Calling `close` twice is the key to reproducing.
+        // It does not matter whether we call `close` twice from the same thread or not.
+        ForkJoinPool.commonPool().execute(() -> cursor.close());
+        ForkJoinPool.commonPool().execute(() -> cursor.close());
+        try {
+            assertNotNull(cursorNext());
+            assertNotNull(cursorNext());
+        } catch (IllegalStateException e) {
+            // one of the expected outcomes, because we call `cursorNext` concurrently with `close`
+        }
+    }
+
     @Test
     @DisplayName("test limit with large documents")
     void testLimitWithLargeDocuments() {