Program: 81439
Project: 81439
Buggy source:
/** 
 * Update   {@link #background} because the board changed.
 */
public void updateBoard(GameStateEvent gameState){
  final Graphics2D g=background.createGraphics();
  g.setRenderingHints(hints);
  final BufferedImage backgroundImage=getCellImage(CellType.CELL_EMPTY,0);
  final Color backgroundColor=new Color(backgroundImage.getRGB(0,0));
synchronized (exclusiveLock) {
    g.setColor(backgroundColor);
    g.fillRect(0,0,boardInfo.pixelSize.width,boardInfo.pixelSize.height);
    final Cell[][] cells=gameState.getCells();
    final int cellSize=boardInfo.cellSize;
    for (int y=boardInfo.gridSize.height - 1; y >= 0; y--) {
      for (int x=boardInfo.gridSize.width - 1; x >= 0; x--) {
        final Cell cell=cells[x][y];
        final CellType type=cell.type;
        final BufferedImage image=getCellImage(type,cell.counter);
        if (image != null) {
          g.drawImage(image,null,x * cellSize,y * cellSize);
        }
      }
    }
    final List<? extends IPlayerSprite> players=gameState.getPlayers();
    for (int playerIndex=0; playerIndex < players.size(); playerIndex++) {
      final IPlayerSprite player=players.get(playerIndex);
      int state=player.getAnimationState();
      int frame=player.getAnimationFrame();
      final int deadState=Player.State.DEAD.ordinal();
      final int dyingState=Player.State.DYING.ordinal();
      if (state == deadState) {
        Integer f=dyingPlayers.get(playerIndex);
        f=(f == null ? 0 : f);
        final int max=images.getMaxSpriteImageFrame(player.getType(),dyingState);
        if (f < max) {
          state=dyingState;
          frame=f;
          dyingPlayers.put(playerIndex,f + 1);
        }
      }
      int animFrame=0;
      if (frame > 0) {
        animFrame=(frame - 1) / images.getSpriteAdvanceRate(player.getType());
        if (state != dyingState && state != deadState) {
          animFrame++;
        }
      }
      BufferedImage image=images.getSpriteImage(player.getType(),state,animFrame);
      if (image != null) {
        final Composite c=g.getComposite();
        if (player.isImmortal()) {
          final float alpha=(globalFrameCounter & 4) != 0 ? 0.25f : 0.8f;
          g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,alpha));
        }
        final Point p=new Point(player.getPosition());
        final Point offset=images.getSpriteOffset(player.getType(),state,frame);
        final Point label=new Point(p);
        p.translate(offset.x,offset.y);
        g.drawImage(image,null,p.x,p.y);
        if (paintPlayerLabels) {
          final String playerLabel=player.getName().toUpperCase();
          g.setFont(labelFont);
          final FontMetrics fm=g.getFontMetrics();
          label.translate(0,-image.getHeight() / 2);
          label.translate(-fm.stringWidth(player.getName()) / 2,-(fm.getDescent() + 2));
          g.setColor(Color.YELLOW);
          g.drawString(playerLabel,label.x,label.y);
        }
        g.setComposite(c);
      }
    }
  }
  g.dispose();
}

Fixed version (ground truth):
/** 
 * Update   {@link #background} because the board changed.
 */
public void updateBoard(GameStateEvent gameState){
  final Graphics2D g=background.createGraphics();
  g.setRenderingHints(hints);
  final BufferedImage backgroundImage=getCellImage(CellType.CELL_EMPTY,0);
  final Color backgroundColor=new Color(backgroundImage.getRGB(0,0));
synchronized (exclusiveLock) {
    g.setColor(backgroundColor);
    g.fillRect(0,0,boardInfo.pixelSize.width,boardInfo.pixelSize.height);
    final Cell[][] cells=gameState.getCells();
    final int cellSize=boardInfo.cellSize;
    for (int y=boardInfo.gridSize.height - 1; y >= 0; y--) {
      for (int x=boardInfo.gridSize.width - 1; x >= 0; x--) {
        final Cell cell=cells[x][y];
        final CellType type=cell.type;
        final BufferedImage image=getCellImage(type,cell.counter);
        if (image != null) {
          g.drawImage(image,null,x * cellSize,y * cellSize);
        }
      }
    }
    final List<? extends IPlayerSprite> players=gameState.getPlayers();
    for (int playerIndex=0; playerIndex < players.size(); playerIndex++) {
      final IPlayerSprite player=players.get(playerIndex);
      int state=player.getAnimationState();
      int frame=player.getAnimationFrame();
      final int deadState=Player.State.DEAD.ordinal();
      final int dyingState=Player.State.DYING.ordinal();
      if (state == deadState) {
        Integer f=dyingPlayers.get(playerIndex);
        f=(f == null ? 0 : f);
        final int max=images.getMaxSpriteImageFrame(player.getType(),dyingState);
        if (f < max) {
          state=dyingState;
          frame=f;
          dyingPlayers.put(playerIndex,f + 1);
        }
      }
 else {
        dyingPlayers.remove(playerIndex);
      }
      int animFrame=0;
      if (frame > 0) {
        animFrame=(frame - 1) / images.getSpriteAdvanceRate(player.getType());
        if (state != dyingState && state != deadState) {
          animFrame++;
        }
      }
      BufferedImage image=images.getSpriteImage(player.getType(),state,animFrame);
      if (image != null) {
        final Composite c=g.getComposite();
        if (player.isImmortal()) {
          final float alpha=(globalFrameCounter & 4) != 0 ? 0.25f : 0.8f;
          g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,alpha));
        }
        final Point p=new Point(player.getPosition());
        final Point offset=images.getSpriteOffset(player.getType(),state,frame);
        final Point label=new Point(p);
        p.translate(offset.x,offset.y);
        g.drawImage(image,null,p.x,p.y);
        if (paintPlayerLabels) {
          final String playerLabel=player.getName().toUpperCase();
          g.setFont(labelFont);
          final FontMetrics fm=g.getFontMetrics();
          label.translate(0,-image.getHeight() / 2);
          label.translate(-fm.stringWidth(player.getName()) / 2,-(fm.getDescent() + 2));
          g.setColor(Color.YELLOW);
          g.drawString(playerLabel,label.x,label.y);
        }
        g.setComposite(c);
      }
    }
  }
  g.dispose();
}