code: public boolean isFresh(final String filename) {
          final FileSystem fileSystem = vertx.fileSystem();
  
          try {
              FileProps fileProps = fileSystem.propsBlocking(filename);
              LRUCache.CacheEntry<String, T> cacheEntry = cache.get(filename);
              final long lastModified = fileProps.lastModifiedTime();
  
              if (cacheEntry == null) {
                  return false;
              }
              if (cacheEntry.isFresh(lastModified)) {
                  return true;
              }
              // not fresh anymore, purge it
              cache.remove(filename);
              return false;
          } catch (RuntimeException e) {
              return false;
          }
      }
docs: Verifies if a file in the filesystem is still fresh against the cache. Errors are treated as not fresh.
  
  @param filename File to look for