code: public FetchObjectResponse fetchObject(String bucketName, String key, String sourceUrl) {
          FetchObjectRequest request = new FetchObjectRequest(bucketName, key, sourceUrl);
          return this.fetchObject(request);
      }
docs: Fetches a source object to a new destination in Bos.
  
  @param bucketName The name of the bucket in which the new object will be created.
  @param key The key in the destination bucket under which the new object will be created.
  @param sourceUrl The url full path for fetching.
  @return A FetchObjectResponse object containing the information returned by Bos for the newly fetching.