title: Hibernate validator for chars
body: <p>Is it possible to validate that a Character is either M or F or do I need to use a string with a regex? </p>
  
  <pre><code>@Pattern(regexp = "^[MF]{1}$", message = "customer.sex.regex")
  private String sex;
  </code></pre>
  
  <p>I would like to use </p>
  
  <pre><code>private Character sex;
  </code></pre>