public static ByteString copyFrom(final byte[] bytes, final int offset,
            final int size)
    {
        final byte[] copy = new byte[size];
        System.arraycopy(bytes, offset, copy, 0, size);
        return new ByteString(copy);
    }
Copies the given bytes into a {@code ByteString}.
protostuff-api/src/main/java/io/protostuff/ByteString.java