schema with `allOf` and `properties` on the same level

[hauner]

the processor ignores the properties of a schema that's using allOf on the same level:

  schema:
    type: object
    allOf:
      - type: object
        properties:
          prop1:
            type: string
    properties:
      prop2:
        type: string

from: openapi-processor/openapi-processor-maven#2