code: public Object getAttribute(final String name) {
          assertActive();
          if (attributes.containsKey(name)) {
              return attributes.get(name);
          }
          Object value = originalSession.getAttribute(name);
          if (value instanceof SerializedObjectHolder) {
              value = ((SerializedObjectHolder) value).getDeserializedObject();
              if (value != null) {
                  attributes.put(name, value);
              } else {
                  originalSession.removeAttribute(name);
              }
          }
          return value;
      }
docs: ==================