 particular it is guaranteed that only one interceptor is used at a time and
  it's always called from AWT thread. Therefore a typical interceptor does not have to use
  any explicit synchronization code (unless it accesses a resource that
  can be simultaneously accessed from other threads of course).
  </p>

  <p>
  However, interceptor types may define a specific protocol, which determines how interceptors
  of that type are chained, what methods are called first, if and what document locks are
  acquire