Backporting PrimitiveCollections class
Motivation: PrimitiveCollections is not in the 4.1 branch. It is needed by HTTP/2. Modifications: Backport this class. Result: PrimitiveCollections is in 4.1.
This commit is contained in:
Scott Mitchell
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/*
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* Copyright 2014 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License, version 2.0 (the
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* "License"); you may not use this file except in compliance with the License. You may obtain a
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* copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under the License
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* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing permissions and limitations under
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* the License.
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*/
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package io.netty.util.collection;
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import io.netty.util.internal.EmptyArrays;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.Iterator;
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import java.util.NoSuchElementException;
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/**
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* Utility methods for primitive collections.
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*/
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public final class PrimitiveCollections {
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private static final IntObjectMap<Object> EMPTY_INT_OBJECT_MAP = new EmptyIntObjectMap();
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private PrimitiveCollections() {
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}
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/**
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* Returns an unmodifiable empty {@link IntObjectMap}.
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*/
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@SuppressWarnings("unchecked")
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public static <V> IntObjectMap<V> emptyIntObjectMap() {
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return (IntObjectMap<V>) EMPTY_INT_OBJECT_MAP;
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}
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/**
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* Creates an unmodifiable wrapper around the given map.
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*/
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public static <V> IntObjectMap<V> unmodifiableIntObjectMap(final IntObjectMap<V> map) {
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return new UnmodifiableIntObjectMap<V>(map);
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}
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/**
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* An empty map. All operations that attempt to modify the map are unsupported.
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*/
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private static final class EmptyIntObjectMap implements IntObjectMap<Object> {
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@Override
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public Object get(int key) {
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return null;
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}
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@Override
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public Object put(int key, Object value) {
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throw new UnsupportedOperationException("put");
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}
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@Override
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public void putAll(IntObjectMap<Object> sourceMap) {
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throw new UnsupportedOperationException("putAll");
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}
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@Override
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public Object remove(int key) {
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throw new UnsupportedOperationException("remove");
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}
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@Override
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public int size() {
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return 0;
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}
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@Override
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public boolean isEmpty() {
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return true;
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}
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@Override
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public void clear() {
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// Do nothing.
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}
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@Override
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public boolean containsKey(int key) {
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return false;
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}
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@Override
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public boolean containsValue(Object value) {
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return false;
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}
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@Override
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public Iterable<Entry<Object>> entries() {
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return Collections.emptySet();
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}
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@Override
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public int[] keys() {
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return EmptyArrays.EMPTY_INTS;
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}
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@Override
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public Object[] values(Class<Object> clazz) {
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return EmptyArrays.EMPTY_OBJECTS;
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}
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@Override
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public Collection<Object> values() {
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return Collections.emptyList();
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}
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}
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/**
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* An unmodifiable wrapper around a {@link IntObjectMap}.
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*
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* @param <V> the value type stored in the map.
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*/
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private static final class UnmodifiableIntObjectMap<V> implements IntObjectMap<V>,
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Iterable<IntObjectMap.Entry<V>> {
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final IntObjectMap<V> map;
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UnmodifiableIntObjectMap(IntObjectMap<V> map) {
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this.map = map;
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}
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@Override
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public V get(int key) {
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return map.get(key);
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}
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@Override
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public V put(int key, V value) {
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throw new UnsupportedOperationException("put");
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}
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@Override
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public void putAll(IntObjectMap<V> sourceMap) {
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throw new UnsupportedOperationException("putAll");
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}
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@Override
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public V remove(int key) {
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throw new UnsupportedOperationException("remove");
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}
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@Override
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public int size() {
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return map.size();
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}
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@Override
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public boolean isEmpty() {
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return map.isEmpty();
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}
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@Override
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public void clear() {
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throw new UnsupportedOperationException("clear");
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}
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@Override
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public boolean containsKey(int key) {
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return map.containsKey(key);
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}
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@Override
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public boolean containsValue(V value) {
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return map.containsValue(value);
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}
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@Override
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public Iterable<Entry<V>> entries() {
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return this;
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}
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@Override
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public Iterator<Entry<V>> iterator() {
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return new IteratorImpl(map.entries().iterator());
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}
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@Override
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public int[] keys() {
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return map.keys();
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}
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@Override
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public V[] values(Class<V> clazz) {
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return map.values(clazz);
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}
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@Override
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public Collection<V> values() {
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return map.values();
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}
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/**
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* Unmodifiable wrapper for an iterator.
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*/
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private class IteratorImpl implements Iterator<Entry<V>> {
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final Iterator<Entry<V>> iter;
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IteratorImpl(Iterator<Entry<V>> iter) {
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this.iter = iter;
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}
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@Override
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public boolean hasNext() {
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return iter.hasNext();
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}
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@Override
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public Entry<V> next() {
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if (!hasNext()) {
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throw new NoSuchElementException();
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}
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return new EntryImpl(iter.next());
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}
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@Override
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public void remove() {
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throw new UnsupportedOperationException("remove");
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}
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}
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/**
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* Unmodifiable wrapper for an entry.
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*/
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private class EntryImpl implements Entry<V> {
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final Entry<V> entry;
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EntryImpl(Entry<V> entry) {
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this.entry = entry;
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}
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@Override
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public int key() {
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return entry.key();
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}
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@Override
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public V value() {
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return entry.value();
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}
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@Override
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public void setValue(V value) {
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throw new UnsupportedOperationException("setValue");
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}
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}
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}
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}
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