/** Implementations of {@code Futures.catching*}. */
@GwtCompatible
@ElementTypesAreNonnullByDefault
@SuppressWarnings({
  // Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
  "ShortCircuitBoolean",
  "nullness", // TODO(b/147136275): Remove once our checker understands & and |.
})
abstract class AbstractCatchingFuture<
        V extends @Nullable Object, X extends Throwable, F, T extends @Nullable Object>