presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/cache/CachingHiveMetastore.java/CachingHiveMetastore/dropRole
class CachingHiveMetastore:    @Override
    public void dropRole(String role)
    {
        try {
            delegate.dropRole(role);
        }
        finally {
            rolesCache.invalidateAll();
            roleGrantsCache.invalidateAll();
        }
    }