code: synchronized final void operationStarted(final int id, @NonNull final ChronosOperation<?> operation,
              @NonNull final Future<?> future
      ) {
          mRunningOperations.put(id, new RunningOperation(operation, future));
      }
docs: Stores the future as a running operation with a given runs' id.
  
  @param id     the unique id of an operation launch
  @param future the object that represents a running operation