17 files declare their use of WebformFormHelper in Webform 6.x

webform.install.update.inc in includes/webform.install.update.inc

Archived Webform update hooks.

WebformCompositeFormElementTrait.php in src/Element/WebformCompositeFormElementTrait.php

WebformComputedBase.php in src/Element/WebformComputedBase.php

WebformDevelEntityFormApiExportForm.php in modules/webform_devel/src/Form/WebformDevelEntityFormApiExportForm.php

WebformDevelEntityFormApiTestForm.php in modules/webform_devel/src/Form/WebformDevelEntityFormApiTestForm.php

WebformElementBase.php in src/Plugin/WebformElementBase.php

WebformElementOptions.php in src/Element/WebformElementOptions.php

WebformFormHelperTest.php in tests/src/Unit/Utility/WebformFormHelperTest.php

WebformHandlerFormBase.php in src/Form/WebformHandlerFormBase.php

WebformHtmlEditor.php in src/Element/WebformHtmlEditor.php

WebformImageSelectElementImages.php in modules/webform_image_select/src/Element/WebformImageSelectElementImages.php

WebformMapping.php in src/Element/WebformMapping.php

WebformOptionsCustom.php in modules/webform_options_custom/src/Element/WebformOptionsCustom.php

WebformOtherBase.php in src/Element/WebformOtherBase.php

WebformTableRow.php in src/Element/WebformTableRow.php

WebformTokenManager.php in src/WebformTokenManager.php

WebformVariantFormBase.php in src/Form/WebformVariantFormBase.php