HELLODATA-1812 - unique user result in search (use hashcode)

hello-data-portal/hello-data-portal-api/src/main/java/ch/bedag/dap/hellodata/portal/user/service/UserService.java

@@ -401,8 +401,7 @@ public List<AdUserDto> searchUser(String email) {
         }
         return userLookupProviderManager.searchUserByEmail(email)
                 .stream()
-                .collect(Collectors.toMap(AdUserDto::getEmail, user -> user, (existing, replacement) -> existing))
-                .values()
+                .collect(Collectors.toCollection(LinkedHashSet::new))
                 .stream()
                 .collect(Collectors.toList());
     }