;; *** before: ***
;; there was no direct check - code either used Java interop or
;; guessed from vector-shaped output of a map's seq
(defn map-entry-old? [x]
  (instance? java.util.Map$Entry x))

(map-entry-old? (first {:a 1}))
;=> true

;; *** in version 1.8: ***
(map-entry? (first {:a 1}))
;=> true
(map-entry? [:a 1])
;=> false