I guess if you fetch groups, with a list of events, that returns groups this could cause some kind of circular reference ? Causing openAPI to not be happy ?

Also I have trouble understanding why ALL the attributes where required. Not only for events. shouldn't really be the MOST important information such as the name, the date etc. ?

I had the same problem with the group. I think the best solution is to create another schemas for event and eventDescription, as i have done with the group below :

Okay but why solving this by creating a whole new schema ? Why having all the attributes as required where by definition we should only have the most important ones ?

because, for example, in the route Get /eventsById, the members is required. So i think it is the best solution to make two descriptions.

But indeed, the fact that we have to re create a all new schema is not perfect.. maybe we could use the AllOf of openAPI, I've already done it for the Get /musicianById like below :

schema: {
              type: 'object',
              allOf: [
                { $ref: '#/components/schemas/musician' },
                {
                  type: 'object',
                  required: ['groups'],
                  properties: {
                    groups: {
                      type: 'array',
                      items: {
                        $ref: '#/components/schemas/groupDescription',
                      },
                    },
                  },
                },
              ],
            },
 ```