docs: public void store(Object obj, ObjectModification mod) throws PersistenceBrokerException
      {
          obj = extractObjectToStore(obj);
          // null for unmaterialized Proxy
          if (obj == null)
          {
              return;
          }
  
          ClassDescriptor cld = getClassDescriptor(obj.getClass());
          // this call ensures that all autoincremented primary key attributes are filled
          Identity oid = serviceIdentity().buildIdentity(cld, obj);
          // select flag for insert / update selection by checking the ObjectModification
          if (mod.needsInsert())
          {
              store(obj, oid, cld, true);
          }
          else if (mod.needsUpdate())
          {
              store(obj, oid, cld, false);
          }
          /*
          arminw
          TODO: Why we need this behaviour? What about 1:1 relations?
          */
          else
          {
              // just store 1:n and m:n associations
              storeCollections(obj, cld, mod.needsInsert());
          }
      }