@VisibleForTesting
  File getStoreLocation(String storeName) {
    return storageManagerUtil.getTaskStoreDir(storeBaseDir, storeName, taskName, taskMode);
  }
Gets the side input SSP offsets for all stores from their local offset files.

@return a {@link Map} of {@link SystemStreamPartition} to offset in the offset files.
samza-core/src/main/java/org/apache/samza/storage/TaskSideInputStorageManager.java