Program: 27542
Project: 27542
Buggy source:
public static ChangeBlockEvent.Break createChangeBlockEventBreak(BlockEvent.BreakEvent forgeEvent){
  final BlockPos pos=forgeEvent.getPos();
  final net.minecraft.world.World world=forgeEvent.getWorld();
  if (world.isRemote) {
    return null;
  }
  final CauseTracker causeTracker=CauseTracker.getInstance();
  final PhaseData data=causeTracker.getCurrentPhaseData();
  BlockSnapshot originalSnapshot=((World)forgeEvent.getWorld()).createSnapshot(pos.getX(),pos.getY(),pos.getZ());
  BlockSnapshot finalSnapshot=BlockTypes.AIR.getDefaultState().snapshotFor(new Location<>((World)world,VecHelper.toVector3d(pos)));
  ImmutableList<Transaction<BlockSnapshot>> blockSnapshots=new ImmutableList.Builder<Transaction<BlockSnapshot>>().add(new Transaction<>(originalSnapshot,finalSnapshot)).build();
  Cause.Builder builder=null;
  User owner=data.context.getOwner().orElse(null);
  User notifier=data.context.getNotifier().orElse(null);
  EntityPlayer player=forgeEvent.getPlayer();
  if (SpongeImplHooks.isFakePlayer(player)) {
    if (owner != null) {
      builder=Cause.source(owner);
      builder.named(NamedCause.FAKE_PLAYER,player);
    }
 else     if (notifier != null) {
      builder=Cause.source(notifier);
      builder.named(NamedCause.FAKE_PLAYER,player);
    }
 else {
      builder=Cause.builder().named(NamedCause.FAKE_PLAYER,player);
    }
  }
  if (builder == null) {
    builder=Cause.source(player);
  }
  if (owner != null) {
    builder.owner(owner);
  }
  if (notifier != null) {
    builder.notifier(notifier);
  }
  builder.named(NamedCause.PLAYER_BREAK,world);
  ChangeBlockEvent.Break spongeEvent=SpongeEventFactory.createChangeBlockEventBreak(builder.build(),blockSnapshots);
  return spongeEvent;
}

Fixed version (ground truth):
public static ChangeBlockEvent.Break createChangeBlockEventBreak(BlockEvent.BreakEvent forgeEvent){
  final BlockPos pos=forgeEvent.getPos();
  final net.minecraft.world.World world=forgeEvent.getWorld();
  if (world.isRemote) {
    return null;
  }
  final CauseTracker causeTracker=CauseTracker.getInstance();
  final PhaseData data=causeTracker.getCurrentPhaseData();
  BlockSnapshot originalSnapshot=((World)forgeEvent.getWorld()).createSnapshot(pos.getX(),pos.getY(),pos.getZ());
  BlockSnapshot finalSnapshot=BlockTypes.AIR.getDefaultState().snapshotFor(new Location<>((World)world,VecHelper.toVector3d(pos)));
  ImmutableList<Transaction<BlockSnapshot>> blockSnapshots=new ImmutableList.Builder<Transaction<BlockSnapshot>>().add(new Transaction<>(originalSnapshot,finalSnapshot)).build();
  Cause.Builder builder=null;
  User owner=data.context.getOwner().orElse(null);
  User notifier=data.context.getNotifier().orElse(null);
  EntityPlayer player=forgeEvent.getPlayer();
  if (SpongeImplHooks.isFakePlayer(player)) {
    Sponge.getCauseStackManager().addContext(EventContextKeys.FAKE_PLAYER,EntityUtil.toPlayer(player));
  }
  Sponge.getCauseStackManager().pushCause(player);
  if (owner != null) {
    Sponge.getCauseStackManager().addContext(EventContextKeys.OWNER,owner);
  }
  if (notifier != null) {
    Sponge.getCauseStackManager().addContext(EventContextKeys.NOTIFIER,notifier);
  }
  Sponge.getCauseStackManager().addContext(EventContextKeys.PLAYER_BREAK,(World)world);
  return SpongeEventFactory.createChangeBlockEventBreak(Sponge.getCauseStackManager().getCurrentCause(),blockSnapshots);
}