docs: private ExtractionGuard placeExtractionGuard(String path) {
          boolean isPrimary;
          CountDownLatch completionLatch;
  
          synchronized( extractionsLock ) {
              completionLatch = extractionLocks.get(path);
  
              if ( completionLatch != null ) {
                  isPrimary = false;
  
              } else {
                  isPrimary = true;
  
                  completionLatch = new CountDownLatch(1);
                  extractionLocks.put(path,  completionLatch);
              }
          }
  
          return new ExtractionGuard(path, isPrimary, completionLatch);
      }