An application/octet-stream response is better than nothing, but should
be avoided whenever possible. Basically I think it's confusing that the
concreteness of the response-type depends on the verbosity of the
accept-header: when the accept-header is just */* one will get
application/octet-stream whenever the method does not specify a concrete
response type (but is annotated with @Produces).
One way to improve this would be to change step 2 of 3.8 so that the
produced-types that are taken from the method or class are compared
against the one taken from the producers and the more concrete of two
compatible types (one from the method and one from the writer) is used.
A different and independent approach would be to expand a */* on the
server to a list of frequent types: if text/html is acceptable and we
can produce it we should deliver this rather than
application/octet-stream, even if it is accepted by a */* or a text/* entry.
Reto