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>

   * @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