segment_update

In the user_data field, the segments can be identified in multiple ways:

• If the segment_key_type is ALTERNATIVE then the segments should use the alternative_id associated with the Segments object being used.
• If the segment_key_type is DEFAULT or not set, the segments should either use an integer corresponding to the segment_id of the Segment object, OR the segment_key of the segment, which is in the format <KEY>-<ID> such as stinger-123.