code: public boolean mergeShard(String shard, Date expireDate) {
          Utils.require(!Utils.isEmpty(shard), "shard");
          try {
              // Send a POST request to "/{application}/_shards/{shard}[?expire-date=<date>]"
              StringBuilder uri = new StringBuilder(Utils.isEmpty(m_restClient.getApiPrefix()) ? "" : "/" + m_restClient.getApiPrefix());          			            
              uri.append("/");
              uri.append(Utils.urlEncode(m_appDef.getAppName()));
              uri.append("/_shards/");
              uri.append(Utils.urlEncode(shard));
              if (expireDate != null) {
                  uri.append("?expire-date=");
                  uri.append(Utils.urlEncode(Utils.formatDateUTC(expireDate)));
              }
              RESTResponse response = m_restClient.sendRequest(HttpMethod.POST, uri.toString());
              m_logger.debug("mergeShard() response: {}", response.toString());
              throwIfErrorResponse(response);
              return true;
          } catch (Exception e) {
              throw new RuntimeException(e);
          }
      }
docs: Request a merge of the OLAP shard with the given name belonging to this session's
  application. Optionally set the shard's expire-date to the given value. True is
  returned if the merge was successful. An exception is thrown if an error occurred.
  
  @param shard         Shard name.
  @param expireDate    Optional value for shard's new expire-date. Leave null if the
  shard should have no expiration date.
  @return              True if the merge was successful.