private void validateSubregionAttributes(RegionAttributes attrs) {
    if (attrs == null) {
      throw new IllegalArgumentException(
          "region attributes must not be null");
    }
    if (scope == Scope.LOCAL && attrs.getScope() != Scope.LOCAL) {
      throw new IllegalStateException(
          "A region with Scope.LOCAL can only have subregions with Scope.LOCAL");
    }
  }
validate attributes of subregion being created, sent to parent

@throws IllegalArgumentException if attrs is null
@throws IllegalStateException if attributes are invalid
geode-core/src/main/java/org/apache/geode/internal/cache/LocalRegion.java