CollapseWhiteSpace RichText — why specified for boolean textChanged?

//----------------------------------
    //  text
    //----------------------------------
    [Inspectable(category="General")]

    // Compiler will strip leading and trailing whitespace from text string.
    [CollapseWhiteSpace]
    
    // The _text storage var is mx_internal in TextBase.
    
    /**
     *  @private
     */
    private var textChanged:Boolean = false;