code: @Override
      public synchronized void close() {
          final int count = INSTANCE.usageCount.get() - 1;
          if (count <= 0) {
              INSTANCE.usageCount.set(0);
              if (searchingAnalyzer != null) {
                  searchingAnalyzer.close();
                  searchingAnalyzer = null;
              }
              if (indexReader != null) {
                  try {
                      indexReader.close();
                  } catch (IOException ex) {
                      LOGGER.trace("", ex);
                  }
                  indexReader = null;
              }
              queryParser = null;
              indexSearcher = null;
              if (index != null) {
                  try {
                      index.close();
                  } catch (IOException ex) {
                      LOGGER.trace("", ex);
                  }
                  index = null;
              }
          }
      }
docs: Closes the CPE Index.