Fix swagger syntax of api.yaml. swagger2 does not support oneOf

[ioggstream]

I expect

syntax of src/tests/api.yaml to be correct

Instead

opening on swagger editor I get the following error:

Structural error at definitions.OneOfTest
should NOT have additional properties
additionalProperty: oneOf
Jump to line 69

Note

This is because gen-api-models supports oneOf schema feature from OAS3. This ticket
could be closed once OAS3 support will be completed:

• the swagger2 schema will remove this test from the yaml
• the openapi3 schema will support this use-case