[WIP] fix: OpenAPI schema with duplicated payload name

[lucasrcezimbra]

I couldn't find any issue/PR reporting this.

When we have two schemas with the same name, only one goes to the OpenAPI schema. I added a test case to show the issue, but I don't know the expected behavior. Options:

1. Add a number in the end Payload, Payload2, PayloadN.
2. Raise an exception during the startup.
3. Add a warning.
4. Any other ideas?