Remove a unused internal class

common/src/main/java/io/netty/util/internal/AtomicFieldUpdaterUtil.java

@@ -1,73 +0,0 @@
-/*
- * Copyright 2012 The Netty Project
- *
- * The Netty Project licenses this file to you under the Apache License,
- * version 2.0 (the "License"); you may not use this file except in compliance
- * with the License. You may obtain a copy of the License at:
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations
- * under the License.
- */
-package io.netty.util.internal;
-
-import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
-import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
-
-final class AtomicFieldUpdaterUtil {
-
-    private static final boolean AVAILABLE;
-
-    static final class Node {
-        volatile Node next;
-    }
-
-    static {
-        boolean available = false;
-        try {
-            AtomicReferenceFieldUpdater<Node, Node> tmp =
-                AtomicReferenceFieldUpdater.newUpdater(
-                        Node.class, Node.class, "next");
-
-            // Test if AtomicReferenceFieldUpdater is really working.
-            Node testNode = new Node();
-            tmp.set(testNode, testNode);
-            if (testNode.next != testNode) {
-                // Not set as expected - fall back to the safe mode.
-                throw new Exception();
-            }
-            available = true;
-        } catch (Throwable t) {
-            // Running in a restricted environment with a security manager.
-        }
-        AVAILABLE = available;
-    }
-
-    static <T, V> AtomicReferenceFieldUpdater<T, V> newRefUpdater(Class<T> tclass, Class<V> vclass, String fieldName) {
-        if (AVAILABLE) {
-            return AtomicReferenceFieldUpdater.newUpdater(tclass, vclass, fieldName);
-        } else {
-            return null;
-        }
-    }
-
-    static <T> AtomicIntegerFieldUpdater<T> newIntUpdater(Class<T> tclass, String fieldName) {
-        if (AVAILABLE) {
-            return AtomicIntegerFieldUpdater.newUpdater(tclass, fieldName);
-        } else {
-            return null;
-        }
-    }
-
-    static boolean isAvailable() {
-        return AVAILABLE;
-    }
-
-    private AtomicFieldUpdaterUtil() {
-        // Unused
-    }
-}