diff --git a/querydsl-postgrest-resttemplate-adapter/src/main/java/fr/ouestfrance/querydsl/postgrest/PostgrestRestTemplate.java b/querydsl-postgrest-resttemplate-adapter/src/main/java/fr/ouestfrance/querydsl/postgrest/PostgrestRestTemplate.java
index 107342e..4a8dfb6 100644
--- a/querydsl-postgrest-resttemplate-adapter/src/main/java/fr/ouestfrance/querydsl/postgrest/PostgrestRestTemplate.java
+++ b/querydsl-postgrest-resttemplate-adapter/src/main/java/fr/ouestfrance/querydsl/postgrest/PostgrestRestTemplate.java
@@ -131,5 +131,4 @@ private URI getUri(String resource, Map<String, List<String>> params) {
         return uriBuilder.build().encode().toUri();
     }
 
-
 }
diff --git a/querydsl-postgrest/src/main/java/fr/ouestfrance/querydsl/postgrest/PostgrestRepository.java b/querydsl-postgrest/src/main/java/fr/ouestfrance/querydsl/postgrest/PostgrestRepository.java
index f3c251c..592cbdc 100644
--- a/querydsl-postgrest/src/main/java/fr/ouestfrance/querydsl/postgrest/PostgrestRepository.java
+++ b/querydsl-postgrest/src/main/java/fr/ouestfrance/querydsl/postgrest/PostgrestRepository.java
@@ -133,11 +133,11 @@ public BulkResponse<T> upsert(List<Object> values, BulkOptions options) {
      * @return map of query params for on conflict if annotation OnConflict is present otherwise empty map
      */
     private Map<String, List<String>> getUpsertQueryParams() {
-        return Optional.ofNullable(this.getClass().getAnnotation(OnConflict.class))
-                .map(OnConflict::columnNames)
-                .map(Arrays::asList)
-                .map(onConflictList-> Map.of(ON_CONFLICT_QUERY_PARAMS, onConflictList))
-                .orElse(Map.of());
+        OnConflict onConflict = this.getClass().getAnnotation(OnConflict.class);
+        if (Objects.nonNull(onConflict)) {
+            return Map.of(ON_CONFLICT_QUERY_PARAMS, List.of(String.join(",", onConflict.columnNames())));
+        }
+        return Collections.emptyMap();
     }
 
     /**