docs: public List<Jid> getBlockList()
              throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
  
          if (blockListCached == null) {
              BlockListIQ blockListIQ = new BlockListIQ();
              BlockListIQ blockListIQResult = connection().createStanzaCollectorAndSend(blockListIQ).nextResultOrThrow();
              blockListCached = blockListIQResult.getBlockedJidsCopy();
          }
  
          return Collections.unmodifiableList(blockListCached);
      }