 wrapper type; 
 <code>String</code>; 
 <code>java.util.Date</code>; 
 <code>java.sql.Date</code>; 
 <code>java.math.BigDecimal</code>;
 <code>java.math.BigInteger</code>.

 <p>The mapped column for the primary key of the entity is assumed 
 to be the primary key of the primary table. If no <code>Column</code> annotation 
 is specified, the primary key column name is assumed to be the name 
 of the primary key property or field.

 <pre>
   Example:

   &#064;Id
   public Long getId() { return id; }
 </pre><