mirror of https://github.com/apache/jclouds.git
added advancing iterable
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4990934470
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162b2f6829
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/**
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* Licensed to jclouds, Inc. (jclouds) under one or more
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* contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. jclouds licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy current 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,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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package org.jclouds.collect;
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import static com.google.common.base.Preconditions.checkNotNull;
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import java.util.Iterator;
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import com.google.common.annotations.Beta;
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import com.google.common.base.Objects;
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import com.google.common.base.Supplier;
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import com.google.common.collect.AbstractIterator;
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import com.google.common.collect.FluentIterable;
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import com.google.common.collect.Iterators;
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import com.google.common.collect.UnmodifiableIterator;
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/**
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* continues to supply iterables until the last was empty
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*
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* @param <E>
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*/
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@Beta
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public class AdvanceUntilEmptyIterable<E> extends FluentIterable<FluentIterable<E>> {
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public static <E> AdvanceUntilEmptyIterable<E> create(Supplier<FluentIterable<E>> nextIterable){
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return new AdvanceUntilEmptyIterable<E>(nextIterable);
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}
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private final AdvanceUntilEmptyIterator<E> iterator;
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protected AdvanceUntilEmptyIterable(Supplier<FluentIterable<E>> nextIterable) {
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this.iterator = new AdvanceUntilEmptyIterator<E>(checkNotNull(nextIterable, "next iterable"));
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}
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@Override
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public Iterator<FluentIterable<E>> iterator() {
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return iterator;
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}
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static class AdvanceUntilEmptyIterator<E> extends AbstractIterator<FluentIterable<E>> {
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private final Supplier<FluentIterable<E>> nextIterable;
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private transient FluentIterable<E> current;
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private transient boolean unread = true;
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AdvanceUntilEmptyIterator(Supplier<FluentIterable<E>> nextIterable) {
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this.nextIterable = checkNotNull(nextIterable, "next iterable");
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}
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/**
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* {@inheritDoc}
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*/
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@Override
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protected FluentIterable<E> computeNext() {
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if (unread)
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try {
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return current = nextIterable.get();
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} finally {
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unread = false;
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}
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else if (current.size() > 0)
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return current = nextIterable.get();
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else
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return endOfData();
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}
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/**
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* {@inheritDoc}
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*/
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@Override
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public int hashCode() {
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return Objects.hashCode(current, unread);
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}
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/**
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* {@inheritDoc}
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*/
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@Override
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public boolean equals(Object obj) {
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if (this == obj)
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return true;
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if (obj == null || getClass() != obj.getClass())
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return false;
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AdvanceUntilEmptyIterator<?> other = AdvanceUntilEmptyIterator.class.cast(obj);
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return Objects.equal(this.current, other.current) && Objects.equal(this.unread, other.unread);
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}
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/**
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* {@inheritDoc}
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*/
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@Override
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public String toString() {
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return Objects.toStringHelper("").omitNullValues().add("current", current).add("unread", unread).toString();
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}
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}
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/**
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* Combines all the pages into a single unmodifiable iterable. ex.
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*
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* <pre>
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* FluentIterable<StorageMetadata> blobs = blobstore.list(...).concat();
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* for (StorageMetadata blob : blobs) {
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* process(blob);
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* }
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* </pre>
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*
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* @see Iterators#concat
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*/
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public FluentIterable<E> concat() {
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final Iterator<FluentIterable<E>> iterator = iterator();
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final UnmodifiableIterator<Iterator<E>> unmodifiable = new UnmodifiableIterator<Iterator<E>>() {
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@Override
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public boolean hasNext() {
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return iterator.hasNext();
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}
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@Override
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public Iterator<E> next() {
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return iterator.next().iterator();
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}
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};
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return new FluentIterable<E>() {
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@Override
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public Iterator<E> iterator() {
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return Iterators.concat(unmodifiable);
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}
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};
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}
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}
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@ -0,0 +1,80 @@
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/**
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* Licensed to jclouds, Inc. (jclouds) under one or more
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* contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. jclouds licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy current 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,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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package org.jclouds.collect;
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import static org.easymock.EasyMock.createMock;
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import static org.easymock.EasyMock.expect;
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import org.easymock.EasyMock;
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import org.testng.Assert;
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import org.testng.annotations.Test;
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import com.google.common.base.Supplier;
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import com.google.common.collect.FluentIterable;
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import com.google.common.collect.ImmutableSet;
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/**
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* Tests behavior of {@code AdvanceUntilEmptyIterable}.
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*
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* @author Adrian Cole
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*/
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@Test(testName = "AdvanceUntilEmptyIterableTest")
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public class AdvanceUntilEmptyIterableTest {
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@SuppressWarnings("unchecked")
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@Test
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public void testSinglePageResultReturnsSame() {
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FluentIterable<String> initial = FluentIterable.from(ImmutableSet.of("foo", "bar"));
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Supplier<FluentIterable<String>> nextIterable = createMock(Supplier.class);
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expect(nextIterable.get()).andReturn(initial);
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EasyMock.replay(nextIterable);
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AdvanceUntilEmptyIterable<String> iterable = new AdvanceUntilEmptyIterable<String>(nextIterable);
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Assert.assertSame(iterable.get(0), initial);
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EasyMock.verify(nextIterable);
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}
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@SuppressWarnings("unchecked")
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@Test
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public void testConcatStopsWhenEmpty() {
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Supplier<FluentIterable<String>> nextIterable = createMock(Supplier.class);
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expect(nextIterable.get()).andReturn(FluentIterable.from(ImmutableSet.of("foo", "bar")));
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expect(nextIterable.get()).andReturn(FluentIterable.from(ImmutableSet.of("boo", "baz")));
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expect(nextIterable.get()).andReturn(FluentIterable.from(ImmutableSet.of("ham", "cheeze")));
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expect(nextIterable.get()).andReturn(FluentIterable.from(ImmutableSet.<String>of()));
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EasyMock.replay(nextIterable);
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AdvanceUntilEmptyIterable<String> iterable = new AdvanceUntilEmptyIterable<String>(nextIterable);
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Assert.assertEquals(iterable.concat().toImmutableSet(),
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ImmutableSet.of("foo", "bar", "boo", "baz", "ham", "cheeze"));
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EasyMock.verify(nextIterable);
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}
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}
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@ -1,3 +1,21 @@
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/**
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* Licensed to jclouds, Inc. (jclouds) under one or more
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* contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. jclouds licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy current 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,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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package org.jclouds.collect;
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import static org.easymock.EasyMock.createMock;
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