@Override
    public int capacity(final ByteBuffer source,
                        final int offset) {
      final byte headerByte0 = source.get(offset);
      final short headerBytes1_2 = source.getShort(offset + 1);
      final int packedCapacity = ((headerByte0 & CAPACITY_MASK_0) << CAPACITY_BITS_1_2)
                                 | (headerBytes1_2 & CAPACITY_MASK_1_2);
      final int capacity = (packedCapacity << OFFSET_BUCKET_BITS)
                           + MIN_CAPACITY;
      assert capacity <= MAX_CAPACITY : "capacity(" + capacity + ") > MAX " + MAX_CAPACITY;
      return capacity;
    }
@Override
    public int capacity(final ByteBuffer source,
                        final int offset)