code: public void addSubEnvelope(TrajectoryEnvelope se) {
  		if (this.subEnvelopes == null) this.subEnvelopes = new ArrayList<TrajectoryEnvelope>();
  		this.subEnvelopes.add(se);
  	}
docs: Add a sub-envelope to this {@link TrajectoryEnvelope}.
  @param se A sub-envelope to add to this {@link TrajectoryEnvelope}.