@Override
  public Map<SystemStreamPartition, String> getOffsetsAfter(Map<SystemStreamPartition, String> offsets) {
    return offsets.entrySet()
        .stream()
        .collect(Collectors.toMap(Map.Entry::getKey, entry -> {
          String offset = entry.getValue();
          return String.valueOf(Integer.valueOf(offset) + 1);
        }));
  }
Fetches the offsets for the messages immediately after the supplied offsets
for a group of SystemStreamPartitions.

@param offsets
         Map from SystemStreamPartition to current offsets.
@return Map from SystemStreamPartition to offsets immediately after the
        current offsets.
samza-core/src/main/java/org/apache/samza/system/inmemory/InMemorySystemAdmin.java