OpenAPI describes and uses types that are generally not part of the standard types for the language runtime:

• Duration: describes a duration (period) following ISO8601 durations
• Time only: describes a time only information (like 4PM)
• Date only: describes a date only information (like a birthdate)

For those type we should:

• check whether the ruby runtime offers a standard type
• check whether there are popular libraries offering an implementation as an alternative
• wrap up the library types in our abstractions library (no need to wrap standard types)
• add serialization/deserialization methods for parse node/serialization writer
• update the implementation for json
• update the ruby refiner to replace the reference to those types before generating the code

more details #1004 and associated PR