HHH-6643

Hi, 

I added the Oracle dialects in the if clause for the bracket adding in the not clause. I also checked the Oracle documentation to verify that the parentheses is standard. 

https://hibernate.onjira.com/browse/HHH-6643

I also added some about the gradle wrappers in README.md to avoid future confusion about the gradle command.

https://hibernate.onjira.com/browse/HHH-7838