int size = c.size();
    if (array.length < size) {
      array = newArray(array, size);
    }
    fillArray(c, array);
    if (array.length > size) {
      @Nullable Object[] unsoundlyCovariantArray = array;
      unsoundlyCovariantArray[size] = null;
    }
    return array;
  }

  /**
   * Implementation of {@link Collection#toArray(Object[])} for collections backed by an object

            if (size() < result.length) {
              // It works around a GWT bug where elements after last is not
              // properly null'ed.
              @Nullable Object[] unsoundlyCovariantArray = result;
              unsoundlyCovariantArray[size()] = null;
            }
            return result;
          }
        });
  }

  @Override
  ImmutableSet<K> createKeySet() {

    int size = c.size();
    if (array.length < size) {
      array = newArray(array, size);
    }
    fillArray(c, array);
    if (array.length > size) {
      @Nullable Object[] unsoundlyCovariantArray = array;
      unsoundlyCovariantArray[size] = null;
    }
    return array;
  }

  /**
   * Implementation of {@link Collection#toArray(Object[])} for collections backed by an object