presto-parser/src/main/java/io/prestosql/sql/parser/AstBuilder.java/AstBuilder/getPrincipalSpecifications
class AstBuilder:    private List<PrincipalSpecification> getPrincipalSpecifications(List<SqlBaseParser.PrincipalContext> principals)
    {
        return principals.stream().map(this::getPrincipalSpecification).collect(toList());
    }