private @Nullable T value;

    @Nullable T get() {
      return value;
    }

    void checkAndSet(@Nullable T expected, @Nullable T newValue) {
      if (value != expected) {
        throw new ConcurrentModificationException();
      }
      value = newValue;
    }

    void clear() {
      value = null;
    }
  }

  private static final class AvlNode<E extends @Nullable Object> {

 * </ul>
 *
 * <p>Usage:
 * <pre>
 * DynamicProperties dynamicProperties = new DynamicProperties("path/to/properties/file");
 * String value = dynamicProperties.getProperty("key");
 * dynamicProperties.setProperty("key", "newValue");
 * dynamicProperties.store();
 * </pre>
 *
 * <p>Exceptions:
 * <ul>
 *   <li>{@link FileAccessException} - Thrown if there are issues accessing the file.</li>

      synchronized (mutex) {
        return delegate().putIfAbsent(key, value);
      }
    }

    @Override
    public boolean replace(K key, V oldValue, V newValue) {
      synchronized (mutex) {
        return delegate().replace(key, oldValue, newValue);
      }
    }

    @Override
    public @Nullable V replace(K key, V value) {
      synchronized (mutex) {

              }

              @Override
              @ParametricNullness
              public V setValue(@ParametricNullness V newValue) {
                checkArgument(apply(getKey(), newValue));
                return super.setValue(newValue);
              }
            };
          }
        };
      }
    }

    @Override
    Set<K> createKeySet() {

              }

              @Override
              @ParametricNullness
              public V setValue(@ParametricNullness V newValue) {
                checkArgument(apply(getKey(), newValue));
                return super.setValue(newValue);
              }
            };
          }
        };
      }
    }

    @Override
    Set<K> createKeySet() {

   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final boolean replace(K key, V oldValue, V newValue) {
    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the map unmodified.
   *
   * @throws UnsupportedOperationException always

        assertFalse(valve.isShowServerInfo());
    }

    @Test
    public void test_defaultSettings() {
        final SuppressErrorReportValve newValve = new SuppressErrorReportValve();
        assertFalse(newValve.isShowReport());
        assertFalse(newValve.isShowServerInfo());
    }

    @Test
    public void test_setShowReport() {
        valve.setShowReport(true);
        assertTrue(valve.isShowReport());

			t.Errorf("no error should happen when assign value to field %v, but got %v", k, err)
		}
	}
	newValues["updated_at"] = time.Time{}
	newValues["active"] = false
	checkField(t, userSchema, reflectValue, newValues)

	// test valuer and other type
	age := myint(10)
	var nilTime *time.Time
	newValues2 := map[string]interface{}{
		"name":       sql.NullString{String: "valuer_and_setter_3", Valid: true},

     * Concatenates values to a destination list, avoiding duplicates.
     * @param dest The destination list.
     * @param newValues The new values to add.
     * @param <T> The type of the values.
     */
    protected static <T> void concatValues(final List<T> dest, final T... newValues) {
        for (final T value : newValues) {
            if (!dest.contains(value)) {
                dest.add(value);
            }
        }
    }

    List<V> oldValues = getCopy(key);
    ListIterator<V> keyValues = new ValueForKeyIterator(key);
    Iterator<? extends V> newValues = values.iterator();

    // Replace existing values, if any.
    while (keyValues.hasNext() && newValues.hasNext()) {
      keyValues.next();
      keyValues.set(newValues.next());
    }

    // Remove remaining old values, if any.
    while (keyValues.hasNext()) {
      keyValues.next();