public RealizationResult create(RegionConfig regionConfig, String regionPath,
      InternalCache cache) {
    RegionFactory factory = getRegionFactory(cache, regionConfig.getRegionAttributes());
    RegionPath regionPathData = new RegionPath(regionPath);
    String regionName = regionPathData.getName();
    String parentRegionPath = regionPathData.getParent();
    if (parentRegionPath == null) {
      factory.create(regionName);
      return new RealizationResult().setMessage("Region successfully created.");
    }

    org.apache.geode.cache.Region parentRegion = cache.getRegion(parentRegionPath);
    factory.createSubregion(parentRegion, regionName);
    return new RealizationResult().setMessage("Region successfully created.");
  }
this method supports creating root region and sub-regions.
We need this because CreateRegionCommand should still
support creating sub regions.

@param regionConfig the name in regionConfig is ignored.
@param regionPath this is the full path of the region
geode-core/src/main/java/org/apache/geode/management/internal/configuration/realizers/RegionConfigRealizer.java