code: @Override
    public Filter adapt(FilterAdapterContext context, PrefixFilter filter)
        throws IOException {
      ByteString.Output output = ByteString.newOutput(filter.getPrefix().length * 2);
      ReaderExpressionHelper.writeQuotedRegularExpression(output, filter.getPrefix());
      // Unquoted all bytes:
      output.write(ReaderExpressionHelper.ALL_QUALIFIERS_BYTES);
      return FILTERS.key().regex(output.toByteString());
    }
docs: {@inheritDoc}