title: What is the difference between javax.persistence.metamodel.Map and java.util.Map?
body: <p>I am trying to write a JDO annotated class in GAE and I want to persist a map. The map is supposed to be an entity field that is a collection of entities hashed by Date. (I am not even sure if this is the right approach).</p>
  
  <p>Eclipse's auto-complete provides me with javax.persistence.metamodel.Map and java.util.Map. What is the difference between these two? What is an example of the former?</p>