On clicked event of form button in D365 X++

Form : SalesQuotationListPage
Button : DH_AmendmentButton
DataSource : SalesQuotationTable

[FormControlEventHandler(formControlStr(SalesQuotationListPage, DH_AmendmentButton), FormControlEventType::Clicked)]
    public static void DH_AmendmentButton_OnClicked(FormControl sender, FormControlEventArgs e)
    {
        FormRun                  fromRunLoc;
        FormDataSource      formDataSourceLoc;
        SalesQuotationTable salesQuoteTable;
        DH_SalesQuote        DHQuote;

        fromRunLoc             = sender.formRun();
        formDataSourceLoc   = sender.formRun().dataSource("SalesQuotationTable");
        salesQuoteTable       = formDataSourceLoc.cursor();
     
        ttsbegin;
        select firstonly forupdate DH_DocumentWorkflowState from DHQuote
            where DHQuote.QuotationId == salesQuoteTable.QuotationId;

        if (DHQuote.DH_DocumentWorkflowState == DH_DocumentWorkflowState::Completed)
        {
            DHQuote.DH_DocumentWorkflowState  = DH_DocumentWorkflowState::NotSubmitted;
            DHQuote.update();
            info("Workflow status changed to draft");
        }
        ttscommit;
    }