code: synchronized void hungup(Date dateOfRemoval, HangupCause hangupCause, String hangupCauseText)
      {
          this.dateOfRemoval = dateOfRemoval;
          this.hangupCause = hangupCause;
          this.hangupCauseText = hangupCauseText;
          // update state and fire PropertyChangeEvent
          stateChanged(dateOfRemoval, ChannelState.HUNGUP);
      }
docs: Sets dateOfRemoval, hangupCause and hangupCauseText and changes state to
  {@link ChannelState#HUNGUP}. Fires a PropertyChangeEvent for state.
  
  @param dateOfRemoval date the channel was hung up
  @param hangupCause cause for hangup
  @param hangupCauseText textual representation of hangup cause