public boolean isUpdate() {
    return update;
  }
Constructor which creates a 'deferred' event. This is used when the value should only be
applied when the object is serialized.

@param session the session from which the value ultimately will be retrieved
@param attribute the name of the attribute
extensions/geode-modules-session-internal/src/main/java/org/apache/geode/modules/session/internal/filter/attributes/DeltaEvent.java