code: JPAPUnitInfo addPU(String puName, JPAPUnitInfo puInfo) {
          synchronized (ivPuList) {
              return ivPuList.put(puName, puInfo);
          }
      }
docs: Adds the puInfo to the collection maintained in this xml info object.
  
  @param puName
  @param puInfo
  @return JPAUnitInfo just added.