presto-spi/src/main/java/io/prestosql/spi/type/NamedTypeSignature.java/NamedTypeSignature/toString
class NamedTypeSignature:    @Override
    public String toString()
    {
        if (fieldName.isPresent()) {
            return format("\"%s\" %s", fieldName.get().getName().replace("\"", "\"\""), typeSignature);
        }
        return typeSignature.toString();
    }