@Override
      public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
        if (pattern.matcher(file.toFile().getName()).matches()) {
          result.add(file.toFile());
        }
        return FileVisitResult.CONTINUE;
      }
Walks the directory and returns all files that match the pattern
@param path
@param pattern
@return List<File>
@throws IOException
ambry-utils/src/main/java/com/github/ambry/utils/Utils.java