code: @Override
      public ProcessTask call() throws Exception {
          try {
              processFiles();
          } catch (UpdateException ex) {
              this.exception = ex;
          } finally {
              settings.cleanup(false);
          }
          return this;
      }
docs: Implements the callable interface.
  
  @return this object
  @throws Exception thrown if there is an exception; note that any
  UpdateExceptions are simply added to the tasks exception collection