@Override
    public List<Region> getRegions() {
        final List<Region> regions = new ArrayList<Region>();

        for (Partition p : partitionMap.values()) {
            for (Map.Entry<String, com.amazonaws.partitions.model.Region>
                    entry : p.getRegions().entrySet()) {
                regions.add(new Region(new PartitionRegionImpl(entry.getKey(),
                        p)));
            }
        }
        return Collections.unmodifiableList(regions);
    }
Region metadata provider based on partitions.
aws-java-sdk-core/src/main/java/com/amazonaws/partitions/PartitionMetadataProvider.java