[littlegrasscao]

Summary

• page GET /shares, GET /shares/{share}/permissions, and GET /recipients with optional maxResults and pageToken query parameters; responses carry nextPageToken while more items remain
• a page holds 500 items when maxResults is missing or 0, and never more; a negative size or a token this server did not issue is INVALID_PARAMETER_VALUE. Treating 0 as unset matches the list APIs of OSS Unity Catalog, which hosts these provider APIs; the recipient protocol lists keep the protocol's meaning of 0 (OpenSharing protocol: authenticate recipients and list granted shares #101)
• page tokens are opaque encodings of an offset into a total order: shares and recipients by name, permissions by recipient name then privilege
• Pagination is a static helper in core with no settings, so neither OpenSharing.Builder nor server.properties configures page sizes
• PATCH /shares/{share}/permissions returns the first page of the share's permissions

Testing

• mvn clean install: 121 tests passed
• PaginationTest: tokens walk a 1200-item list in pages of 500, larger sizes are capped at 500, 0 pages like a missing size, and negative sizes and foreign tokens are rejected
• ProviderListPaginationTest: with maxResults=2, each list walks page by page in order without duplicates, PATCH permissions returns the first page, maxResults=0 returns a full page, and a bad maxResults or pageToken is 400

Stacked on #100.