@Override
  public Map<SystemStreamPartition, String> getOffsetsAfter(Map<SystemStreamPartition, String> offsets) {
    Map<SystemStreamPartition, String> offsetsAfter = new HashMap<SystemStreamPartition, String>();

    for (SystemStreamPartition systemStreamPartition : offsets.keySet()) {
      offsetsAfter.put(systemStreamPartition, null);
    }

    return offsetsAfter;
  }
A SystemAdmin that returns a constant set of partitions for all streams.
samza-test/src/main/java/org/apache/samza/system/mock/MockSystemAdmin.java