Include isAccessibleForFree for universally free events

[nickevansuk]

Rule name

Include isAccessibleForFree for universally free events

Rule type

Data quality warning

Rule hint

Universally free events are sometimes rendered differently or specifically included by some data users, so if an event is free to all it's worth tagging it to get extra publicity.

Associated proposal or model reference

• Describing free events, advanced booking requirements, etc openactive/modelling-opportunity-data#98

Examples

• Include isAccessibleForFree for universally free events openactive/implementation-tracker#137

[ldodds]

Suggest we generate a warning if there is a single Offer with a price of zero, and recommend adding the property.

We still need the zero price Offer though to make the Event bookable.