@SuppressWarnings("unchecked") protected SetJoin<UserEntity, ExtensionFieldValueEntity> createOrGetJoin( String alias, Root<UserEntity> root, SetAttribute<UserEntity, ExtensionFieldValueEntity> attribute) { for (Join<UserEntity, ?> currentJoin : root.getJoins()) { if (currentJoin.getAlias() == null) { // if alias is null, it is not an alias for an extension join, so we ignore it continue; } if (currentJoin.getAlias().equals(alias)) { return (SetJoin<UserEntity, ExtensionFieldValueEntity>) currentJoin; } } final SetJoin<UserEntity, ExtensionFieldValueEntity> join = root.join(attribute, JoinType.LEFT); join.alias(alias); return join; }