code: private boolean hasNullifiedFK(FieldDescriptor[] fkFieldDescriptors, Object[] fkValues)
      {
          boolean result = true;
          for (int i = 0; i < fkValues.length; i++)
          {
              if (!pb.serviceBrokerHelper().representsNull(fkFieldDescriptors[i], fkValues[i]))
              {
                  result = false;
                  break;
              }
          }
          return result;
      }
docs: to avoid creation of unmaterializable proxies