StringField validate logic makes all string fields required regardless of required flag value

[clockard]

When using the StringField as part of a new field class the underlying validate will cause the string field to always be required. StringField calls it super.validate which checks the required flag but the StringField validate then goes on to check if the field value is empty and adds an exception if it is without checking if it is required or not.

[avalexxx]

Whenever a value is provided for a field, it is validated, not just when marked required. This is to ensure optional fields are still validated through the same validation flow. If the client doesn't want a field to be validated, they should not be specifying the field in the request.

[avalexxx]

A majority of the time, an empty string is an invalid input. If there is a use case where an empty string should be a valid value, I would prefer to have a field extend StringField and override validate.