code: public <T> Callable<T> asCallable(final RetryCallback<T, Exception> callback) {
          return new Callable<T>() {
              public T call() throws Exception {
                 return ExtendedRetryTemplate.this.execute(callback);
  
              }
          };
      }
docs: *
  Construct a {@link Callable} which wraps the given {@link RetryCallback},
  and who's {@link java.util.concurrent.Callable#call()} method will execute
  the callback via this {@link ExtendedRetryTemplate}
  
  @param callback The callback to wrap
  @param <T> The return type of the callback
  @return The callback as a Callable