Removed space from min_access_level attribute name (#302).

src/main/java/org/gitlab4j/api/models/GroupFilter.java

@@ -136,7 +136,7 @@ public class GroupFilter {
             .withParam("statistics", statistics)
             .withParam("with_custom_attributes", withCustomAttributes)
             .withParam("owned", owned)  
-            .withParam("min_access_level ", accessLevel)
+            .withParam("min_access_level", accessLevel)
         );
     }
 }