Remove unused async cursor tryNext support

Inline method that's now only used in one place.

JAVA-3972

Author: jyemin

driver-core/src/main/com/mongodb/internal/operation/AsyncQueryBatchCursor.java

@@ -151,7 +151,32 @@ public void close() {
 
     @Override
     public void next(final SingleResultCallback<List<T>> callback) {
-        internalNext(callback);
+        if (isClosed()) {
+            callback.onResult(null, new MongoException("next() called after the cursor was closed."));
+        } else if (firstBatch != null && (!firstBatch.getResults().isEmpty())) {
+            // May be empty for a tailable cursor
+            List<T> results = firstBatch.getResults();
+            firstBatch = null;
+            if (getServerCursor() == null) {
+                close();
+            }
+            callback.onResult(results, null);
+        } else {
+            ServerCursor localCursor = getServerCursor();
+            if (localCursor == null) {
+                close();
+                callback.onResult(null, null);
+            } else {
+                synchronized (this) {
+                    if (isClosed()) {
+                        callback.onResult(null, new MongoException("next() called after the cursor was closed."));
+                        return;
+                    }
+                    isOperationInProgress = true;
+                }
+                getMore(localCursor, callback);
+            }
+        }
     }
 
     @Override
@@ -193,35 +218,6 @@ public int getMaxWireVersion() {
         return maxWireVersion;
     }
 
-    private void internalNext(final SingleResultCallback<List<T>> callback) {
-        if (isClosed()) {
-            callback.onResult(null, new MongoException("next() called after the cursor was closed."));
-        } else if (firstBatch != null && (!firstBatch.getResults().isEmpty())) {
-            // May be empty for a tailable cursor
-            List<T> results = firstBatch.getResults();
-            firstBatch = null;
-            if (getServerCursor() == null) {
-                close();
-            }
-            callback.onResult(results, null);
-        } else {
-            ServerCursor localCursor = getServerCursor();
-            if (localCursor == null) {
-                close();
-                callback.onResult(null, null);
-            } else {
-                synchronized (this) {
-                    if (isClosed()) {
-                        callback.onResult(null, new MongoException("next() called after the cursor was closed."));
-                        return;
-                    }
-                    isOperationInProgress = true;
-                }
-                getMore(localCursor, callback);
-            }
-        }
-    }
-
     private boolean limitReached() {
         return Math.abs(limit) != 0 && count.get() >= Math.abs(limit);
     }