* @author Harry Heymann
 * @since 2.0
 */
@GwtCompatible
public interface Supplier<T extends @Nullable Object> {
  /**
   * Retrieves an instance of the appropriate type. The returned object may or may not be a new
   * instance, depending on the implementation.
   *
   * @return an instance of the appropriate type
   */
  @ParametricNullness
  T get();

  /**

  internal val delegate: RealConnectionPool,
) {
  internal constructor(
    maxIdleConnections: Int = 5,
    keepAliveDuration: Long = 5,
    timeUnit: TimeUnit = TimeUnit.MINUTES,
    taskRunner: TaskRunner = TaskRunner.INSTANCE,
    connectionListener: ConnectionListener = ConnectionListener.NONE,
  ) : this(
    RealConnectionPool(
      taskRunner = taskRunner,
      maxIdleConnections = maxIdleConnections,

   *
   * @since 13.0
   * @since 4.0 (in Equivalences)
   */
  public static Equivalence<Object> identity() {
    return Identity.INSTANCE;
  }

  static final class Equals extends Equivalence<Object> implements Serializable {

    static final Equals INSTANCE = new Equals();

    @Override
    protected boolean doEquivalent(Object a, Object b) {
      return a.equals(b);
    }

    @Override

  }

  Optional() {}

  /**
   * Returns {@code true} if this holder contains a (non-null) instance.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> no differences.
   */
  public abstract boolean isPresent();

  /**
   * Returns the contained instance, which must be present. If the instance might be absent, use
   * {@link #or(Object)} or {@link #orNull} instead.
   *

      // Put types estimated to be the most frequent first.
      if (value instanceof CharSequence) {
        return ((CharSequence) value).length() == 0;
      } else if (value instanceof Collection) {
        return ((Collection<?>) value).isEmpty();
      } else if (value instanceof Map) {
        return ((Map<?, ?>) value).isEmpty();
      } else if (value instanceof Optional) {
        return !((Optional) value).isPresent();

    for (Constructor<X> constructor : preferringStringsThenThrowables(constructors)) {
      X instance = newFromConstructor(constructor, cause);
      if (instance != null) {
        if (instance.getCause() == null) {
          instance.initCause(cause);
        }
        return instance;
      }
    }
    throw new IllegalArgumentException(
        "No appropriate constructor for exception of type "

  <version>0.0.0.0</version>
</parent>
    ]]></configuration>
    <description> This is the MavenProject instance for the parent of the current POM.
    </description>
  </expression>
  <expression>
    <syntax>project.file</syntax>
    <description> This is the File instance that refers to the location of the current POM on
      disk.
    </description>
  </expression>
  <expression>

    this.comparator = comparator;
    checkState((type == Type.SORTED) == (comparator != null));
  }

  /** Returns an instance which specifies that no ordering is guaranteed. */
  public static <S> ElementOrder<S> unordered() {
    return new ElementOrder<>(Type.UNORDERED, null);
  }

  /**
   * Returns an instance which specifies that ordering is guaranteed to be always be the same across

    this.comparator = comparator;
    checkState((type == Type.SORTED) == (comparator != null));
  }

  /** Returns an instance which specifies that no ordering is guaranteed. */
  public static <S> ElementOrder<S> unordered() {
    return new ElementOrder<>(Type.UNORDERED, null);
  }

  /**
   * Returns an instance which specifies that ordering is guaranteed to be always be the same across

        File tempFile = createTempFile("pomTest");
        FileModelSource instance = new FileModelSource(tempFile);

        assertFalse(instance.equals(null), "Expected " + instance + " to not equal " + null);
        assertFalse(instance.equals(new Object()));
        assertTrue(instance.equals(instance), "Expected " + instance + " to equal " + instance);
        assertTrue(instance.equals(new FileModelSource(tempFile)));
    }

    @Test