title: Does it make sense to create entity table with only ID attribute?
body: <p>Does it make sense to create a single entity when it should only contain the <code>@Id</code> value as a String?</p>
  
  <pre><code>@Entity
  class CountryCode {
     @Id
     String letterCode; //GBR, FRA, etc
  }
  
  @Entity
  class Payment {
     CountryCode code;
     // or directly without further table: String countryCode;
  }
  </code></pre>
  
  <p>Or would you just use the letterCode as the stringvalue instead of creating the <code>CountryCode</code> entity?</p>
  
  <p>It should later be possible for example to fetch all payments that contain a specific countrycode. This might be possible with both solutions. But which is the better one (why)?</p>