public Collection<Theme> themes(ThemeFilter filter) {
        return get(Theme.class, (filter != null) ? filter : new ThemeFilter());
    }
public Collection < Theme > themes ( ThemeFilter filter ) { return get ( Theme . class , ( filter != null ) ? filter : new ThemeFilter ( ) ) ; }
Get themes filtered by the criteria specified in the passed in filter.

@param filter Limit the items returned. If null, then all items returned.
@return Collection of items as specified in the filter.