MK
(reduce-kv (fn [acc k v]
(assoc acc k
(reduce-kv (fn [acc k v]
(assoc acc k (if (nil? v) "" v))) {} v)))
{}
{:person
{:firstName nil
:lastName nil
:middleName nil}
:practitioner
{:firstName "1", :lastName nil, :middleName nil, :id "pr2", :role ""}})
;; => {:person {:firstName "", :lastName "", :middleName ""}, :practitioner {:firstName "1", :lastName "", :middleName "", :id "pr2", :role ""}}