code: public List<Persistence.PersistenceUnit> getPersistenceUnit() {
          if (persistenceUnit == null) {
              persistenceUnit = new ArrayList<Persistence.PersistenceUnit>();
          }
          return this.persistenceUnit;
      }
docs: Gets the value of the persistenceUnit property.
  
  <p>
  This accessor method returns a reference to the live list,
  not a snapshot. Therefore any modification you make to the
  returned list will be present inside the JAXB object.
  This is why there is not a <CODE>set</CODE> method for the persistenceUnit property.
  
  <p>
  For example, to add a new item, do as follows:
  <pre>
  getPersistenceUnit().add(newItem);
  </pre>
  
  
  <p>
  Objects of the following type(s) are allowed in the list
  {@link Persistence.PersistenceUnit }