I don't think this breaks caching. The 'fields' param is part of the query string and should be used as part of any key used for the cache.
I'll contend it does make retrieving from the cache less likely to occur since different clients may have different values for 'fields'. That said, I've anecdotally found that using a reasonably good default value for 'fields' (with associated reasonably small JSON body) means most clients end up not having to send 'fields' anyways. This makes the cache hit rate stay high.
I'll contend it does make retrieving from the cache less likely to occur since different clients may have different values for 'fields'. That said, I've anecdotally found that using a reasonably good default value for 'fields' (with associated reasonably small JSON body) means most clients end up not having to send 'fields' anyways. This makes the cache hit rate stay high.