10 files declare their use of FieldMappingBase in Webform Content Creator 3.x

AddressFieldMapping.php in src/Plugin/WebformContentCreator/FieldMapping/AddressFieldMapping.php

BooleanFieldMapping.php in src/Plugin/WebformContentCreator/FieldMapping/BooleanFieldMapping.php

DateTimeFieldMapping.php in src/Plugin/WebformContentCreator/FieldMapping/DateTimeFieldMapping.php

DefaultFieldMapping.php in src/Plugin/WebformContentCreator/FieldMapping/DefaultFieldMapping.php

EmailFieldMapping.php in src/Plugin/WebformContentCreator/FieldMapping/EmailFieldMapping.php

EntityReferenceFieldMapping.php in src/Plugin/WebformContentCreator/FieldMapping/EntityReferenceFieldMapping.php

LinkFieldMapping.php in src/Plugin/WebformContentCreator/FieldMapping/LinkFieldMapping.php

NumericFieldMapping.php in src/Plugin/WebformContentCreator/FieldMapping/NumericFieldMapping.php

SocialMediaLinksFieldMapping.php in src/Plugin/WebformContentCreator/FieldMapping/SocialMediaLinksFieldMapping.php

TextFieldMapping.php in src/Plugin/WebformContentCreator/FieldMapping/TextFieldMapping.php