* fix: ExampleGenerator correctly generates allOf composed schemas
Changes the previous behavior of generating `null` examples for allOf composed schemas.
Fixes#17497
* fix: ExampleGenerator correctly generates anyOf and oneOf composed schemas
Changes the previous behavior of generating `null` examples for anyOf and oneOf composed schemas.
To generate a oneOf/anyOf example, we generate the example using the first valid schema available. In case of a $ref, we use the first valid reference.
Fixes#17497