private static Map<TaskName, Integer> changelogPartitionMapping(int numPartitions) {
    return IntStream.range(0, numPartitions)
        .boxed()
        .collect(Collectors.toMap(TestJobModelCalculator::taskName, Function.identity()));
  }
Unfortunately, we still need powermock for testing the regex topic flow, since that flow checks for a specific
rewriter class, and setting up the support for that specific class is too cumbersome.
Many of the tests do not need powermock.
samza-core/src/test/java/org/apache/samza/coordinator/TestJobModelCalculator.java