docs: private void submitBuffer(boolean forceCommit) {
          int size = docBuffer.size();
          if (size > 0) {
              // Debugging
              // String age = String.valueOf(
              // ((new Date().getTime()) - bufferOldest) / 1000);
              // String length = String.valueOf(bufferSize);
              // log.debug("Submitting buffer: " + size + " documents, " + length
              // +
              // " bytes, " + age + "s");
              log.debug("=== Submitting buffer: " + size + " documents");
  
              // Concatenate all documents in the buffer
              StringBuffer submissionBuffer = new StringBuffer();
              for (String doc : docBuffer.keySet()) {
                  submissionBuffer.append(docBuffer.get(doc));
                  // log.debug("DOC: {}", doc);
              }
  
              // Submit if the result is valid
              if (submissionBuffer.length() > 0) {
                  // Wrap in the basic Solr 'add' node
                  String submission = submissionBuffer.insert(0, "<add>")
                          .append("</add>").toString();
                  // And submit
                  try {
                      solr.request(new DirectXmlRequest("/update", submission));
                  } catch (Exception ex) {
                      log.error("Error submitting documents to Solr!", ex);
                  }
                  // Commit if required
                  if (autoCommit || forceCommit) {
                      log.info("Running forced commit!");
                      try {
                          // HTTP commits for embedded
                          if (commit != null) {
                              solr.commit();
                              commit.commit();
                              // or just HTTP on it's own
                          } else {
                              solr.commit();
                          }
                      } catch (Exception e) {
                          log.warn(
                                  "Solr forced commit failed. Document will"
                                          + " not be visible until Solr autocommit fires."
                                          + " Error message: {}", e);
                      }
                  }
              }
          }
          purgeBuffer();
      }