* ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
   * types (or if the type is a non-variable type, like {@code String}), then code should almost
   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
   * its runtime check.
   *
   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code

                }
            }
            return null;
        }
    }

    /**
     * Ensures that expressions referring to URLs evaluate to normalized URLs.
     *
     */
    static class UrlNormalizingPostProcessor implements InterpolationPostProcessor {

        private static final Set<String> URL_EXPRESSIONS;

   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
   * types (or if the type is a non-variable type, like {@code String}), then code should almost
   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
   * its runtime check.
   *
   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code

   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
   * types (or if the type is a non-variable type, like {@code String}), then code should almost
   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
   * its runtime check.
   *
   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code

   * such as:
   *
   * - Make checkOpen return the non-null `seq`. Then callers can assign that to a local variable or
   *   even back to `this.seq`. However, that may suggest that we're defending against concurrent
   *   mutation, which is not an actual risk because we use `synchronized`.
   * - Make `remaining` require a non-null `seq` argument. But this is a bit weird because the

    return new NullRemovalListener<>();
  }

  /** Type-inferring factory method for creating a {@link QueuingRemovalListener}. */
  @GwtIncompatible // ConcurrentLinkedQueue
  static <K, V> QueuingRemovalListener<K, V> queuingRemovalListener() {
    return new QueuingRemovalListener<>();
  }

  /** Type-inferring factory method for creating a {@link CountingRemovalListener}. */

    return new NullRemovalListener<>();
  }

  /** Type-inferring factory method for creating a {@link QueuingRemovalListener}. */
  @GwtIncompatible // ConcurrentLinkedQueue
  static <K, V> QueuingRemovalListener<K, V> queuingRemovalListener() {
    return new QueuingRemovalListener<>();
  }

  /** Type-inferring factory method for creating a {@link CountingRemovalListener}. */

   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
   * types (or if the type is a non-variable type, like {@code String}), then code should almost
   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
   * its runtime check.
   *
   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code

   * <p>Instances of {@code exceptionClass} are created by choosing an arbitrary public constructor
   * that accepts zero or more arguments, all of type {@code String} or {@code Throwable}
   * (preferring constructors with at least one {@code String}, then preferring constructors with at
   * least one {@code Throwable}) and calling the constructor via reflection. If the exception did