// since get returned null, try a putIfAbsent; that fails due to a simulated race
    when(backingMap.putIfAbsent(eq(KEY), isA(AtomicInteger.class))).thenReturn(existingZero);
    // since the putIfAbsent returned a zero, we'll try to replace...
    when(backingMap.replace(eq(KEY), eq(existingZero), isA(AtomicInteger.class))).thenReturn(false);
    // ...and then putIfAbsent. Simulate failure on both

    while (true) {
      AtomicInteger existingCounter = safeGet(countMap, element);
      if (existingCounter == null) {
        existingCounter = countMap.putIfAbsent(element, new AtomicInteger(occurrences));
        if (existingCounter == null) {
          return 0;
        }
        // existingCounter != null: fall through to operate against the existing AtomicInteger
      }

    }
  }

  public void testPutIfAbsent() {
    TestMap map = new TestMap();
    map.put("foo", 1);
    assertEquals(Integer.valueOf(1), map.putIfAbsent("foo", 2));
    assertEquals(Integer.valueOf(1), map.get("foo"));
    assertThat(map.putIfAbsent("bar", 3)).isNull();
    assertEquals(Integer.valueOf(3), map.get("bar"));
  }

  public void testRemove() {
    TestMap map = new TestMap();
    map.put("foo", 1);

    map.putAll(ImmutableMap.of(two, three));
    assertThat(map.get(two)).isSameInstanceAs(three);
    assertThat(map.putIfAbsent(one, three)).isSameInstanceAs(two);
    assertThat(map.get(one)).isSameInstanceAs(two);
    assertThat(map.putIfAbsent(three, one)).isNull();
    assertThat(map.get(three)).isSameInstanceAs(one);
    assertThat(map.replace(one, three)).isSameInstanceAs(two);

                String key = coreExtension.getGroupId() + ":" + coreExtension.getArtifactId();
                CoreExtension conflict = selectedExtensions.putIfAbsent(key, coreExtension);
                if (conflict != null && !Objects.equals(coreExtension.getVersion(), conflict.getVersion())) {
                    conflicts.add(String.format(

   * zero, associate it with {@code newValue}. Returns the previous value associated with {@code
   * key}, or zero if there was no mapping for {@code key}.
   */
  long putIfAbsent(K key, long newValue) {
    AtomicBoolean noValue = new AtomicBoolean(false);
    Long result =
        map.compute(
            key,
            (K k, @Nullable Long oldValue) -> {

        Entry<Object, Object> entry = warmed.get(i - WARMUP_MIN);
        Object newValue = new Object();
        assertThat(cache.asMap().putIfAbsent(entry.getKey(), newValue))
            .isSameInstanceAs(entry.getValue());
        Object newKey = new Object();
        assertThat(cache.asMap().putIfAbsent(newKey, entry.getValue())).isNull();
        // this getUnchecked() call shouldn't be a cache miss; verified below

        Entry<Object, Object> entry = warmed.get(i - WARMUP_MIN);
        Object newValue = new Object();
        assertThat(cache.asMap().putIfAbsent(entry.getKey(), newValue))
            .isSameInstanceAs(entry.getValue());
        Object newKey = new Object();
        assertThat(cache.asMap().putIfAbsent(newKey, entry.getValue())).isNull();
        // this getUnchecked() call shouldn't be a cache miss; verified below

    assertThat(cache.getIfPresent(10)).isEqualTo(50);
    assertThat(asMap.get(10)).isEqualTo(50);
    assertThat(cache.getIfPresent(2)).isNull();
    assertThat(asMap.get(2)).isNull();

    asMap.putIfAbsent(2, 20);
    asMap.putIfAbsent(10, 20);

    assertThat(cache.getIfPresent(2)).isEqualTo(20);
    assertThat(asMap.get(2)).isEqualTo(20);
    assertThat(cache.getIfPresent(10)).isEqualTo(50);

            if (!Modifier.isStatic(method.getModifiers()) && method.getParameterCount() == 1) {
                Type[] paramTypes = method.getGenericParameterTypes();
                methodMap.putIfAbsent(method.getName(), new MethodInfo(method, paramTypes[0]));
            }
        }

        return methodMap;
    }

    /**
     * Check if method is compatible with value type.
     */