Hello team, While working on OpenAPI spec version upgrade from 3.0.x to 3.1.x for Apache Polaris, I noticed the OpenAPI spec used by Iceberg is actually an invalid 3.1.x.
Per https://learn.openapis.org/upgrading/v3.0-to-v3.1.html#replace-nullable-with-type-arrays, nullable should be replace with type arrays when migrating from v3.0.x to v3.1.x. I had raised https://github.com/apache/iceberg/pull/18428 to address this issue. Please take a look. Thanks, Yong
