presto-parser/src/main/java/io/prestosql/sql/tree/GrantorSpecification.java/GrantorSpecification/GrantorSpecification
class GrantorSpecification:    public GrantorSpecification(Type type, Optional<PrincipalSpecification> principal)
    {
        this.type = requireNonNull(type, "type is null");
        this.principal = requireNonNull(principal, "principal is null");
    }