title: Validating String Literal Type with class-validator
body: <p>I have this type:</p>
  
  <pre><code>export type BranchOperatorRole = 'none' | 'seller' | 'operator' | 'administrator';
  </code></pre>
  
  <p>With which class-validator decorator can I validate that a property has one of those values?</p>
  
  <pre><code>import { IsEmail, IsString, Contains } from "class-validator";
  
  export type BranchOperatorRole = 'none' | 'seller' | 'operator' | 'administrator';
  
  export class AddBranchOperatorRequest extends User {
  
      @IsEmail()
      email: string;
  
      @Contains(BranchOperatorRole )
      role: BranchOperatorRole;
  
  }
  
  </code></pre>