OneOf, nested inside of another OneOf is not shown as "oneOf" on documentation page
I am developing a Spring app with OpenApi.
For open API spec (schema.txt) java code is generated by the maven code generator plugin.
Model validation is working fine.
But the documentation page in my app (localhost.png) and on editor.swagger.io (editor.swagger.io.png) looks different.
Be aware, that it is a simplified version of OneOf object locally for presentation reasons.
OneOf inside of another OneOf is shown as a field, but not as "oneOf": see a red marker on "localhost.png".
I manually put it on root level to show how it is expected: see blue marker on "localhost.png".
Is it something wrong with my code?
How i can fix it?