presto-rcfile/src/main/java/io/prestosql/rcfile/binary/BinaryEncoding.java/BinaryEncoding/encodeValueInto
class BinaryEncoding:    @Override
    public void encodeValueInto(Block block, int position, SliceOutput output)
    {
        Slice slice = type.getSlice(block, position);
        // Note binary nested in complex structures do no use the empty marker.
        // Therefore, empty VARBINARY values are ok.
        writeVInt(output, slice.length());
        output.writeBytes(slice);
    }