public PartitionedRegion getPartitionedRegion() {
    // TODO - this model really should not have
    // a reference to the partitioned region object.
    // The fixed PR code currently depends on this
    // partitioned region object and needs
    // refactoring.
    return partitionedRegion;
  }
Add a region to the model. All regions that are added are assumed to be colocated. The first
region added to the model should be the parent region. The parent region is expected to have at
least as many members as child regions; it may have more. If the parent has more members than
child regions those members will be considered invalid.

@param memberDetailSet A set of details about each member.
geode-core/src/main/java/org/apache/geode/internal/cache/partitioned/rebalance/model/PartitionedRegionLoadModel.java