Create a Custom script validator for Workflow Transition

[G Ashok]

Hi, 

I need help to Create a Custom script validator Workflow Transition: Validator  

here are my requirement  

1. Create a Custom script validator that if AAA (Customfield) = GR (Customfield Value) then Story Points and Due Date fields are required fields
2. Create a Custom script validator that if AAA (Customfield) = GR or AR (Customfield Value) then no fields are required.
3. Create a Custom script validator that if AAA (Customfield) = GR, PR or AR (Customfield Value) then Story Points, Sprint, and Epic Link are required.