presto-phoenix/src/main/java/io/prestosql/plugin/phoenix/PhoenixTableProperties.java/PhoenixTableProperties/getRowkeys
class PhoenixTableProperties:    public static Optional<List<String>> getRowkeys(Map<String, Object> tableProperties)
    {
        requireNonNull(tableProperties);

        String rowkeysCsv = (String) tableProperties.get(ROWKEYS);
        if (rowkeysCsv == null) {
            return Optional.empty();
        }
        return Optional.of(Arrays.asList(StringUtils.split(rowkeysCsv, ',')));
    }