Rule Definition
There can be situations in which it is necessary to protect a whole class from uncontrolled specialization. This could be suitable, for example, if changes must be made to a class without any subclasses becoming syntactically or semantically incorrect. For a final definition, use the FINAL addition in the CLASS statement.

Remediation
Check if the class could be inherited. If not, then add the FINAL addition in its definition.

Violation Code Sample

* This class must not be subclassed
CLASS counter DEFINITION.
PUBLIC SECTION.
    METHODS: 
        set 
            IMPORTING VALUE
                (set_value) TYPE i, increment,
        get 
            EXPORTING VALUE
                (get_value) TYPE i.
PRIVATE SECTION.
    DATA count TYPE i.
ENDCLASS.

Fixed Code Sample

* This class must not be subclassed
CLASS counter DEFINITION FINAL.
PUBLIC SECTION.
    METHODS: 
        set 
            IMPORTING VALUE
                (set_value) TYPE i, increment,
        get 
            EXPORTING VALUE
                (get_value) TYPE i.
PRIVATE SECTION.
    DATA count TYPE i.
ENDCLASS.

An insider's guide to writing robust, understandable, maintainable, state-of-the-art ABAP programs - Part 2 Andreas Blumenthal - Horst Keller