code: public ObjectMetadata getObjectMetadata(String bucketName, String key) {
          return this.getObjectMetadata(new GetObjectMetadataRequest(bucketName, key));
      }
docs: Gets the metadata for the specified Bos object without actually fetching the object itself.
  This is useful in obtaining only the object metadata, and avoids wasting bandwidth on fetching
  the object data.
  
  <p>
  The object metadata contains information such as content type, content disposition, etc.,
  as well as custom user metadata that can be associated with an object in Bos.
  
  @param bucketName The name of the bucket containing the object's whose metadata is being retrieved.
  @param key The key of the object whose metadata is being retrieved.
  @return All Bos object metadata for the specified object.