title: Java Bean Validation (JSR303) constraints involving relationship between several bean properties
body: <p>Say I have the following simple java bean:</p>
  
  <pre><code>class MyBean {
     private Date startDate;
     private Date endDate;
     //setter, getters etc...
  }
  </code></pre>
  
  <p>Is there a mechanism in JSR 303 to create a custom validator that validates the constraint that startDate must be before endDate?</p>
  
  <p>It seems to me to be a common use case, yet I cannot find any examples of this kind of multiple property relationsship constraint.</p>