Thanks to Finastra policy "we are open", it s possible to download the OAS specification even without beeing sign in !
then between JSON or YML this is ISO functional format ,
Line of Business exposes either one or the others format, following usually OAS2.0 spec , only for few use case OAS 3.0 is used ( usually to handle complex payload / polymorphism )
Moving from YML to JSON or vice versa can be easily acheived by using open source tooling, or even online service . Notably SmartBear propose https://editor.swagger.io/ that allow you to do the conversion from one to the other format
4 People are following this question.