docs: public void modifyColumnFamilyRule() {
      System.out.printf("%nUpdating column family %s GC rule%n", COLUMN_FAMILY_1);
      // [START bigtable_update_gc_rule]
      // Updates the column family metadata to update the GC rule.
      // Updates a column family GC rule.
      VersionRule versionRule = GCRULES.maxVersions(1);
      try {
        // ModifyColumnFamiliesRequest can be used both for adding and modifying families, here it is
        // being used to modify a family
        // Updates column family with given GC rule.
        ModifyColumnFamiliesRequest updateRequest =
            ModifyColumnFamiliesRequest.of(tableId).updateFamily(COLUMN_FAMILY_1, versionRule);
        adminClient.modifyFamilies(updateRequest);
        System.out.printf("Column family %s GC rule updated%n", COLUMN_FAMILY_1);
      } catch (NotFoundException e) {
        System.err.println("Failed to modify a non-existent column family: " + e.getMessage());
      }
      // [END bigtable_update_gc_rule]
    }