public Map<Integer, ReplicaPlacementInfo> replicasToMoveBetweenDisksByBroker() {
    return Collections.unmodifiableMap(_replicasToMoveBetweenDisksByBroker);
  }
@Test
  public void testIntraBrokerReplicaMovements() {
    ExecutionProposal p = new ExecutionProposal(TP, 0, _r0d0, Arrays.asList(_r0d0, _r1d1), Arrays.asList(_r0d1, _r1d1));
    Assert.assertEquals(1, p.replicasToMoveBetweenDisksByBroker().size());
  }