title: Why does JPA require a no-arg constructor for domain objects?
body: <p>Why does JPA require a no-arg constructor for domain objects?
  I am using eclipselink and just got this exception during deployment.</p>
  
  <pre><code>Exception [EclipseLink-63] (Eclipse Persistence Services-1.1.0.r3639-SNAPSHOT): 
  org.eclipse.persistence.exceptions.DescriptorException
  
  Exception Description: The instance creation method   
  [com.me.model.UserVO.&lt;Default Constructor&gt;], with no parameters, 
    does not exist, or is not accessible.
  Internal Exception: java.lang.NoSuchMethodException: 
    com.me.model.UserVO.&lt;init&gt;()
  Descriptor: RelationalDescriptor(com.me.model.UserVO --&gt; 
    [DatabaseTable(user)])
  </code></pre>