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Whether a successful tileset.json body for url should be persisted to the blob cache. Providers whose first response is a redirect envelope rather than a real tileset (Cesium Ion's /endpoint returns {type, url, accessToken}) return false so it never gets cached as if it were tileset content. Default true — root and subtree tileset.json bodies cache normally and replay across sessions, with the embedded session/auth tokens reused as long as the server still accepts them.