tc, ok := r.Context().Value(mcontext.ContextTraceKey).(*mcontext.TraceCtxt)
		if ok {
			tc.FuncName = funcName
			tc.ResponseRecorder.LogErrBody = true
		}

		mfs, err := gatherers.Gather()
		if err != nil && len(mfs) == 0 {
			writeErrorResponseJSON(r.Context(), w, toAdminAPIErr(r.Context(), err), r.URL)
			return
		}

		contentType := expfmt.Negotiate(r.Header)