Hi! I have a question about this section of the spec:
"Although relationships can be modified along with resources (as described above), JSON API also supports updating of relationships independently at URLs from relationship links."
So, I understand that the relationships can be modified through PATCH requests to the resource itself (something like
books/1), or by PATCH requests to relationship links (something like
/books/1/relationships/author). But is the server also required to support relationship links/updates through relationship links, or is that optional?
Thanks in advance!