code: @Test public void many(){
    DuplicateMessageFilter dmf=new DuplicateMessageFilter();
    dmf.setAllowedRepetitions(0);
    int cacheSize=10;
    int margin=2;
    dmf.setCacheSize(cacheSize);
    dmf.start();
    for (int i=0; i < cacheSize + margin; i++) {
      assertEquals(FilterReply.NEUTRAL,dmf.decide(null,null,null,"a" + i,null,null));
    }
    for (int i=cacheSize - 1; i >= margin; i--) {
      assertEquals(FilterReply.DENY,dmf.decide(null,null,null,"a" + i,null,null));
    }
    for (int i=margin - 1; i >= 0; i--) {
      assertEquals(FilterReply.NEUTRAL,dmf.decide(null,null,null,"a" + i,null,null));
    }
  }
  