title: Grails:Try to validate just part of properties of command object but get a exception
body: <p>According to official docs I can pass a list of properties as a parameter to <code>validate()</code>.
  But when I try to call <code>validate()</code> on a command object like this:</p>
  
  <pre><code>groupCmd.validate(['startDate'])
  </code></pre>
  
  <p>I get a exception like following:</p>
  
  <pre><code>groovy.lang.MissingMethodException: No signature of method: GroupCommand.validate() is     
  applicable for argument types: (java.util.ArrayList) values: [[startDate]]
  </code></pre>
  
  <p>Does this mean only when using <code>validate()</code> on a domain class instance, you can pass a list of properties to be validated, but not on a command object?</p>
  
  <p>And is there some ways to just validate some of properties of a command object?</p>
  
  <p>And I use grails 1.3.7</p>
  
  <p>Best Regards<br/>
  Thanks to Mualig for formatting my article</p>