Remove allowEmptyValue from REST Catalog OpenAPI Spec

[elphastori]

Feature Request / Improvement

Background

Follow-up on dev@ mailing list thread which discussed the drawbacks of using allowEmptyValue in our REST Catalog OpenAPI specification and proposed removing it: https://lists.apache.org/thread/pg2obnmlhkdfg2gtbd0xo4j9zqwlcxf4

Key points raised:

• allowEmptyValue is deprecated – see OAI/OpenAPI-Specification#1632 and Published OpenAPI Specification
• It creates ambiguity and already forced us to add special handling in PR Core: Improve pagination logic to handle null pageToken #13129 so that an omitted pageToken in the first paginated request is legal.
• Community consensus so far: +1 from @nastra

Proposal

• Remove every occurrence of allowEmptyValue from rest-catalog-open-api.yaml.
• Keep current behaviour backwards-compatible until the next major release by treating the absence of pageToken and parent (and similar query params) exactly as today.

Query engine

None

Willingness to contribute

• I can contribute this improvement/feature independently
• I would be willing to contribute this improvement/feature with guidance from the Iceberg community
• I cannot contribute this improvement/feature at this time