public interface Dirtyable
Dirtyable interface indicate
  that they are able to track their own dirty state.boolean isDirty()
true if the data in the object has been modified.void markDirty(boolean dirty)
markDirty(...) instead of
  setDirty(...) so that the JavaBeans
  Introspector will not
  mistakenly identify "dirty" as a JavaBean property.dirty - If true, sets the object as being
  dirty; if false, sets the object as being up-to-date.