title: How to cleanup the JdbcMetadataStore?
body: <p>Initially our flow of cimmunicating with google Pub/Sub was so:</p>
  
  <ol>
  <li>Application accepts message  </li>
  <li>Checks that it doesn't exist in idempotencyStore  </li>
  <li>3.1 If doesn't exist - put it into idempotency store (key is a value of unique header, value is a current timestamp)<br>
  3.2 If exist - just ignore this message  </li>
  <li>When processing is finished  - send acknowledge  </li>
  <li>In the acknowledge successfull callback - remove this msg from metadatastore</li>
  </ol>
  
  <p>The point 5 is wrong because theoretically we can get duplicated message even after message has processed. Moreover we found out that sometimes message might not be removed even although successful callback was invoked( <a href="https://stackoverflow.com/questions/59391264/message-is-received-from-google-pub-sub-subscription-again-and-again-after-ackno">Message is received from Google Pub/Sub subscription again and again after acknowledge[Heisenbug]</a>) So we decided to update value after message is proccessed and replace timestamp with "FiNISHED" string</p>
  
  <p>But sooner or later we will encounter that this table will be overcrowded. So we have to cleanup messages in the MetaDataStore. We can remove messages which are processed and they were processed more 1 day.</p>
  
  <p>As was mentioned in the comments of <a href="https://stackoverflow.com/a/51845202/2674303">https://stackoverflow.com/a/51845202/2674303</a> I can add additional column in the metadataStore table where I could mark if message is processed. It is not a problem at all. But how can I use this flag in the my cleaner? MetadataStore has only key and value</p>