Builds against main (and potentially other versions) are encountering issues related to the valuesIt() method used by the clusterService when it tries to look at the list of indices.

/home/runner/work/security/security/src/main/java/org/opensearch/security/privileges/PrivilegesEvaluator.java:652: error: cannot find symbol
                   return clusterService.state().getMetadata().getIndices().valuesIt();

These changes are the result of the Core refactor to no longer use ImmutableOpenMap.

Originally posted by @willyborankin in #2557 (comment)