KEYCLOAK-2705

services/src/main/java/org/keycloak/services/resources/admin/GroupResource.java

@@ -212,7 +212,7 @@ public class GroupResource {
             throw new NotFoundException("Could not find group by id");
         }
 
-        firstResult = firstResult != null ? firstResult : -1;
+        firstResult = firstResult != null ? firstResult : 0;
         maxResults = maxResults != null ? maxResults : Constants.DEFAULT_MAX_RESULTS;
 
         List<UserRepresentation> results = new ArrayList<UserRepresentation>();

services/src/main/java/org/keycloak/storage/UserStorageManager.java

@@ -379,6 +379,8 @@ public class UserStorageManager implements UserProvider, OnUserCache {
 
     protected List<UserModel> query(PaginatedQuery pagedQuery, RealmModel realm, int firstResult, int maxResults) {
         if (maxResults == 0) return Collections.EMPTY_LIST;
+        if (firstResult < 0) firstResult = 0;
+        if (maxResults < 0) maxResults = Integer.MAX_VALUE - 1;
 
         List<UserQueryProvider> storageProviders = getStorageProviders(session, realm, UserQueryProvider.class);
         // we can skip rest of method if there are no storage providers