presto-jdbc/src/main/java/io/prestosql/jdbc/PrestoResultSet.java/PrestoResultSet/getFieldMap
class PrestoResultSet:    private static Map<String, Integer> getFieldMap(List<Column> columns)
    {
        Map<String, Integer> map = new HashMap<>();
        for (int i = 0; i < columns.size(); i++) {
            String name = columns.get(i).getName().toLowerCase(ENGLISH);
            if (!map.containsKey(name)) {
                map.put(name, i + 1);
            }
        }
        return ImmutableMap.copyOf(map);
    }