bug fix

themis-admin/src/main/java/com/qmth/themis/admin/api/TBUserController.java

@@ -621,7 +621,7 @@ public class TBUserController {
         }
         Gson gson = new Gson();
         TBUser tbUser = gson.fromJson(gson.toJson(mapParameter), TBUser.class);
-        if (Objects.isNull(tbUser.getPassword()) || Objects.equals(tbUser.getPassword(), "")) {
+        if ((Objects.isNull(tbUser.getPassword()) || Objects.equals(tbUser.getPassword(), "")) && Objects.nonNull(dbUser)) {
             tbUser.setPassword(dbUser.getPassword());
         }
         List<String> roleList = (List<String>) mapParameter.get("roleCode");