SENTRY-1475 is tracking the integration between Solr 7 and Sentry. Currently admin privileges for Solr are defined using "admin" as the collection name (i.e. Sentry reuses collection level permissions for admin operations).
Solr 7, on the other hand, provides a pluggable authorization framework with fine-grained permissions model. Specifically it provides pre-defined permissions for admin operations (viz. collection-admin and core-admin etc.). Hence we need an upgrade tool to migrate the existing permissions (written for Solr 4) to this new permissions model supported by Solr 7.