}

  public void testGetOnlyElement_withDefault_singleton() {
    Iterable<String> iterable = singletonList("foo");
    assertEquals("foo", getOnlyElement(iterable, "bar"));
  }

  public void testGetOnlyElement_withDefault_empty() {
    Iterable<String> iterable = emptyList();
    assertEquals("bar", getOnlyElement(iterable, "bar"));
  }

import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
import static com.google.common.collect.Iterables.getOnlyElement;

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.io.Serializable;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.EnumMap;

   * @throws IllegalArgumentException if the iterable contains multiple elements
   */
  @ParametricNullness
  public static <T extends @Nullable Object> T getOnlyElement(Iterable<T> iterable) {
    return Iterators.getOnlyElement(iterable.iterator());
  }

  /**
   * Returns the single element contained in {@code iterable}, or {@code defaultValue} if the
   * iterable is empty.
   *

    List<Future<String>> results;

    results = service.invokeAll(callables);
    assertThat(getOnlyElement(results)).isInstanceOf(TrustedListenableFutureTask.class);

    results = service.invokeAll(callables, 1, SECONDS);
    assertThat(getOnlyElement(results)).isInstanceOf(TrustedListenableFutureTask.class);

    /*
     * TODO(cpovirk): move ForwardingTestCase somewhere common, and use it to

  }

  public void testGetOnlyElement_withDefault_singleton() {
    Iterable<String> iterable = singletonList("foo");
    assertEquals("foo", getOnlyElement(iterable, "bar"));
  }

  public void testGetOnlyElement_withDefault_empty() {
    Iterable<String> iterable = emptyList();
    assertEquals("bar", getOnlyElement(iterable, "bar"));
  }

 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Iterables.getOnlyElement;
import static com.google.common.collect.Tables.immutableCell;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

   * @throws IllegalArgumentException if the iterable contains multiple elements
   */
  @ParametricNullness
  public static <T extends @Nullable Object> T getOnlyElement(Iterable<T> iterable) {
    return Iterators.getOnlyElement(iterable.iterator());
  }

  /**
   * Returns the single element contained in {@code iterable}, or {@code defaultValue} if the
   * iterable is empty.
   *

 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Iterables.getOnlyElement;
import static com.google.common.collect.Tables.immutableCell;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

    }
  }

  public void testWriteThroughEntry() {
    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked(1);
      Entry<Object, Object> entry = Iterables.getOnlyElement(cache.asMap().entrySet());

      cache.invalidate(1);
      assertEquals(0, cache.size());

      entry.setValue(3);
      assertEquals(1, cache.size());
      assertEquals(3, cache.getIfPresent(1));

    IllegalStateException ex = new IllegalStateException(re);

    assertThat(getCausalChain(ex)).containsExactly(ex, re, iae, sue).inOrder();
    assertSame(sue, Iterables.getOnlyElement(getCausalChain(sue)));

    List<Throwable> causes = getCausalChain(ex);
    assertThrows(UnsupportedOperationException.class, () -> causes.add(new RuntimeException()));
  }