Program: 34675
Project: 34675
Buggy source:
/** 
 * Generates the dungeon.
 */
@Override public boolean generate(StructureWorld world,Random rand){
  int targetAmount=minPieces + rand.nextInt(maxPieces - minPieces + 1);
  StructureDungeonPiece startPiece=startingPiece == null ? pieces.getRandomItem(rand) : startingPiece;
  addPiece(startPiece,Pos.at(-startPiece.size.sizeX / 2,sizeY / 2 - startPiece.size.sizeY / 2,-startPiece.size.sizeZ));
  for (int cycleAttempt=0, count; cycleAttempt < 1000; cycleAttempt++) {
    StructureDungeonPiece nextPiece=selectNextPiece(rand);
    if (nextPiece == null)     continue;
    Connection nextPieceConnection=nextPiece.getRandomConnection(rand);
    for (int placeAttempt=0; placeAttempt < 10; placeAttempt++) {
      StructureDungeonPieceInst connected=weightedInstances.getRandomItem(rand);
      if (cycleConnections(connected,nextPieceConnection.facing,rand,connection -> {
        Pos aligned=alignConnections(connected,connection,nextPieceConnection);
        if (canPlaceArea(aligned,aligned.offset(nextPiece.size.sizeX,nextPiece.size.sizeY,nextPiece.size.sizeZ))) {
          addPiece(nextPiece,aligned);
          return true;
        }
 else         return false;
      }
)) {
        if (connected.getWeight() == 0)         weightedInstances.remove(connected);
        if (generated.size() >= targetAmount)         cycleAttempt=Integer.MAX_VALUE;
        break;
      }
    }
  }
  if (!MathUtil.inRangeIncl(generated.size(),minPieces,maxPieces))   return false;
  for (  StructureDungeonPiece piece : pieces) {
    if (!MathUtil.inRangeIncl(pieceCount.get(piece),piece.minAmount,piece.maxAmount))     return false;
  }
  for (  StructureDungeonPieceInst pieceInst : generated) {
    pieceInst.piece.generate(world,rand,pieceInst.boundingBox.getTopLeft());
  }
  return true;
}

Fixed version (ground truth):
/** 
 * Generates the dungeon.
 */
@Override public boolean generate(StructureWorld world,Random rand){
  int targetAmount=minPieces + rand.nextInt(maxPieces - minPieces + 1);
  StructureDungeonPiece startPiece=startingPiece == null ? pieces.getRandomItem(rand) : startingPiece;
  addPiece(startPiece,Pos.at(-startPiece.size.sizeX / 2,sizeY / 2 - startPiece.size.sizeY / 2,-startPiece.size.sizeZ));
  for (int cycleAttempt=0, count; cycleAttempt < 1000; cycleAttempt++) {
    StructureDungeonPiece nextPiece=selectNextPiece(rand);
    if (nextPiece == null)     continue;
    Connection nextPieceConnection=nextPiece.getRandomConnection(rand);
    for (int placeAttempt=0; placeAttempt < 10; placeAttempt++) {
      StructureDungeonPieceInst connected=weightedInstances.getRandomItem(rand);
      if (cycleConnections(connected,nextPieceConnection.facing,rand,connection -> {
        Pos aligned=alignConnections(connected,connection,nextPieceConnection);
        if (canPlaceArea(aligned,aligned.offset(nextPiece.size.sizeX,nextPiece.size.sizeY,nextPiece.size.sizeZ))) {
          addPiece(nextPiece,aligned);
          return true;
        }
 else         return false;
      }
)) {
        if (connected.getWeight() == 0)         weightedInstances.remove(connected);
        if (generated.size() >= targetAmount)         cycleAttempt=Integer.MAX_VALUE;
        break;
      }
    }
  }
  if (!MathUtil.inRangeIncl(generated.size(),minPieces,maxPieces))   return false;
  for (  StructureDungeonPiece piece : pieces) {
    if (!MathUtil.inRangeIncl(pieceCount.get(piece),piece.minAmount,piece.maxAmount))     return false;
  }
  for (  StructureDungeonPieceInst pieceInst : generated) {
    pieceInst.piece.generate(world,rand,pieceInst.boundingBox.x1,pieceInst.boundingBox.y1,pieceInst.boundingBox.z1);
  }
  return true;
}