1.True, 6.8 is indeed ancient but I am not aware of any security/breaking issues that are fixed between the latest 6.8 and 7.17. It is planned anyway
2.In the case that I don't fetch seqNo/primaryTerm, then what is the function of retry_on_conflict? it is server side logic as far as I can tell but I see no way for elasticsearch to know the "correct" seqNo/primaryTerm from my request
3.wait_for exists in 6.8 as well and from the docs it looks like a "weaker" version of true. Is conflict resolution different when using wait_for?
For example we have 3 update requests for the same document - using wait_for or true seems to be like it lead to the same outcome: a conflict will occur and won't be solved by ES