docs: @SuppressWarnings("unchecked") // worse case should be a ClassCastException
    /*
     * TODO(cpovirk): Consider requiring key to be a K here. But AtomicLongMapSubject isn't currently
     * parameterized, and if we're going to add a type parameter, I'd rather wait until after we
     * (hopefully) remove the other existing type parameters.
     */
    public void containsEntry(Object key, long value) {
      checkNotNull(key, "AtomicLongMap does not support null keys");
      long actualValue = ((AtomicLongMap<Object>) actual()).get(key);
      if (actualValue != value) {
        failWithActual("expected to contain entry", immutableEntry(key, value));
      }
    }