presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/file/FileHiveMetastore.java/FileHiveMetastore/listRoleGrants
class FileHiveMetastore:    @Override
    public synchronized Set<RoleGrant> listRoleGrants(HivePrincipal principal)
    {
        ImmutableSet.Builder<RoleGrant> result = ImmutableSet.builder();
        if (principal.getType() == USER) {
            result.add(new RoleGrant(principal.toPrestoPrincipal(), PUBLIC_ROLE_NAME, false));
            if (ADMIN_USERS.contains(principal.getName())) {
                result.add(new RoleGrant(principal.toPrestoPrincipal(), ADMIN_ROLE_NAME, true));
            }
        }
        result.addAll(listRoleGrantsSanitized().stream()
                .filter(grant -> HivePrincipal.from(grant.getGrantee()).equals(principal))
                .collect(toSet()));
        return result.build();
    }