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

        @SuppressWarnings("unchecked")
        String indexColumns = (String) tableProperties.get(INDEX_COLUMNS);
        if (indexColumns == null) {
            return Optional.empty();
        }

        return Optional.of(Arrays.asList(StringUtils.split(indexColumns, ',')));
    }