public void removeBufferLinesBefore( long minTimeBoundary ) {
    buffer.values().stream().filter( v -> v.getEvent().timeStamp < minTimeBoundary ).forEach( v -> buffer.remove( v.getNr() ) );
  }
@Test
  public void testRemoveBufferLinesBefore() {
    LoggingBuffer loggingBuffer = new LoggingBuffer( 100 );
    for ( int i = 0; i < 40; i++ ) {
      KettleLoggingEvent event = new KettleLoggingEvent();
      event.setMessage( new LogMessage( "test", LogLevel.BASIC ) );
      event.setTimeStamp( i );
      loggingBuffer.addLogggingEvent( event );
    }
    loggingBuffer.removeBufferLinesBefore( 20 );
    Assert.assertEquals( 20, loggingBuffer.size() );
  }