BP error 'parameter not used' d365 AX
Add the below text at the end with comma
,SuppressBPWarning('BPParameterNotUsed', "Parameter required" - to end of the decorator.
E.g.
[FormDataFieldEventHandler(formDataFieldStr(aForm, aDatasource, aField), FormDataFieldEventType::Validating),SuppressBPWarning('BPParameterNotUsed', "Parameter required")
]