/**
   * A collector that converts a stream of zero or one elements to an {@code Optional}.
   *
   * @throws IllegalArgumentException if the stream consists of two or more elements.
   * @throws NullPointerException if any element in the stream is {@code null}.
   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be

import static com.google.common.collect.testing.Helpers.assertContentsInOrder;
import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;
import static com.google.common.collect.testing.features.CollectionSize.ONE;
import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static java.util.Arrays.asList;

## Adding Guava to your build

Guava's Maven group ID is `com.google.guava`, and its artifact ID is `guava`.
Guava provides two different "flavors": one for use on a (Java 8+) JRE and one
for use on Android or by any library that wants to be compatible with Android.
These flavors are specified in the Maven version field as either `33.5.0-jre` or
`33.5.0-android`. For more about depending on Guava, see

    assertNull(navigableSet.pollLast());
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ONE)
  public void testSingletonSetPollFirst() {
    assertEquals(a, navigableSet.pollFirst());
    assertTrue(navigableSet.isEmpty());
  }

  @CollectionSize.Require(ONE)
  public void testSingletonSetNearby() {
    assertNull(navigableSet.lower(e0()));
    assertEquals(a, navigableSet.floor(e0()));

import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;
import static com.google.common.collect.testing.features.CollectionSize.ONE;
import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;

import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;
import static com.google.common.collect.testing.features.CollectionSize.ONE;
import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;

 */

package com.google.common.collect.testing.google;

import static com.google.common.collect.testing.features.CollectionFeature.NON_STANDARD_TOSTRING;
import static com.google.common.collect.testing.features.CollectionSize.ONE;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_KEYS;

import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_ITERATOR_REMOVE;
import static com.google.common.collect.testing.features.CollectionSize.ONE;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.Multimap;
import com.google.common.collect.testing.features.CollectionFeature;

    @Override
    public BigInteger next(BigInteger value) {
      return value.add(BigInteger.ONE);
    }

    @Override
    public BigInteger previous(BigInteger value) {
      return value.subtract(BigInteger.ONE);
    }

    @Override
    BigInteger offset(BigInteger origin, long distance) {
      checkNonnegative(distance, "distance");

        .any(gradle.startParameter.taskNames::contains)


/**
 * Returns a new provider that takes its value from at most one
 * of the given providers. If no input provider is present, the output
 * provider will not be present. If more than one input provider
 * has a value specified, the resulting provider will throw an
 * exception when queried.
 */