e.g. run package check on
cl_dd_ddl_handler_factory=>create( ).
cl_abap_dbfeatures=>use_features( requested_features = VALUE #( ) ).
You will get a warning for cl_dd_ddl_handler_factory (but not for cl_abap_dbfeatures).
Triggering F1 for cl_abap_dbfeatures will show ABAP-documentation
(nothing for cl_dd_ddl_handler_factory).