code: static void unboundSfsbFromExtendedPC(JPAExPcBindingContext bindingContext)
      {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              Tr.entry(tc, "unboundSfsbFromExtendedPC : " + bindingContext);
  
          JPAPuId puIds[] = bindingContext.getExPcPuIds();
          long bindId = bindingContext.getBindId();
  
          // New this binding key only once and update the puid in the loop
          ExPcBindingKey bindingKey = new ExPcBindingKey(bindId, null);
          for (JPAPuId puId : puIds)
          {
              bindingKey.puId = puId;
              ExPcBindingInfo exPcBindingInfo = svExPcBindingMap.remove(bindingKey);
              if (exPcBindingInfo != null)
              {
                  // JPA 5.9.1 Container Responsibilities
                  //
                  // The container closes the entity manager by calling EntityManager.close after the
                  // stateful session bean and all other stateful session beans that have inherited
                  // the same persistence context as the EntityManager have been removed.
                  if (exPcBindingInfo.removeRemovedOrDiscardedSfsb(bindingKey) == 0)
                  {
                      EntityManager em = exPcBindingInfo.getEntityManager();
                      if (em != null)
                      {
                          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled())
                              Tr.debug(tc, "All SFSBs using the same extend-scoped persistence "
                                           + "context have been removed, closing EntityManager " + em);
                          if (em.isOpen()) // d442445
                              em.close();
                      }
                  }
              }
          }
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              Tr.exit(tc, "unboundSfsbFromExtendedPC : exPcBindMap size=" + svExPcBindingMap.size());
      }
docs: When SFSB instances are removed or discard, this method is called to unbind the SFSB from the
  associated persistence context. When the last SFSB is removed from the bound collection, the
  associated EntityManager is closed.
  
  @param bindingContext
  to be unbound