Program: 55752
Project: 55752
Buggy source:
public void placeObject(MapObject object,int x,int y){
  ObjectContainer container=null;
  ProtectContainer protector=ProtectContainer.getInstance();
  Set<ELandscapeType> landscapes=null;
  if (object instanceof MapTreeObject) {
    container=TreeObjectContainer.getInstance();
  }
 else   if (object instanceof MapStoneObject) {
    container=new StoneObjectContainer((MapStoneObject)object);
  }
 else   if (object instanceof MovableObject) {
    container=new MovableObjectContainer((MovableObject)object,x,y);
  }
 else   if (object instanceof StackObject) {
    container=new StackContainer((StackObject)object);
  }
 else   if (object instanceof BuildingObject) {
    container=new BuildingContainer((BuildingObject)object,new ShortPoint2D(x,y));
    landscapes=((BuildingObject)object).getType().getGroundTypes();
    protector=new ProtectLandscapeConstraint(((BuildingObject)object).getType());
  }
 else   if (object instanceof MapDecorationObject) {
    container=new MapObjectContainer((MapDecorationObject)object);
  }
 else {
    return;
  }
  boolean allowed=true;
  ShortPoint2D start=new ShortPoint2D(x,y);
  for (  RelativePoint p : container.getProtectedArea()) {
    ShortPoint2D abs=p.calculatePoint(start);
    if (!contains(abs.x,abs.y) || objects[abs.x][abs.y] != null || !landscapeAllowsObjects(getLandscape(abs.x,abs.y)) || !landscapes.contains(getLandscape(abs.x,abs.y))) {
      allowed=false;
    }
  }
  if (allowed) {
    for (    RelativePoint p : container.getProtectedArea()) {
      ShortPoint2D abs=p.calculatePoint(start);
      objects[abs.x][abs.y]=protector;
      undoDelta.removeObject(abs.x,abs.y);
    }
    objects[x][y]=container;
    undoDelta.removeObject(x,y);
  }
}

Fixed version (ground truth):
public void placeObject(MapObject object,int x,int y){
  ObjectContainer container;
  ProtectContainer protector=ProtectContainer.getInstance();
  Set<ELandscapeType> landscapes=null;
  if (object instanceof MapTreeObject) {
    container=TreeObjectContainer.getInstance();
  }
 else   if (object instanceof MapStoneObject) {
    container=new StoneObjectContainer((MapStoneObject)object);
  }
 else   if (object instanceof MovableObject) {
    container=new MovableObjectContainer((MovableObject)object,x,y);
  }
 else   if (object instanceof StackObject) {
    container=new StackContainer((StackObject)object);
  }
 else   if (object instanceof BuildingObject) {
    container=new BuildingContainer((BuildingObject)object,new ShortPoint2D(x,y));
    landscapes=((BuildingObject)object).getType().getGroundTypes();
    protector=new ProtectLandscapeConstraint(((BuildingObject)object).getType());
  }
 else   if (object instanceof MapDecorationObject) {
    container=new MapObjectContainer((MapDecorationObject)object);
  }
 else {
    return;
  }
  boolean allowed=true;
  ShortPoint2D start=new ShortPoint2D(x,y);
  for (  RelativePoint p : container.getProtectedArea()) {
    ShortPoint2D abs=p.calculatePoint(start);
    if (!contains(abs.x,abs.y) || objects[abs.x][abs.y] != null || !landscapeAllowsObjects(getLandscape(abs.x,abs.y)) || (landscapes != null && !landscapes.contains(getLandscape(abs.x,abs.y)))) {
      allowed=false;
    }
  }
  if (allowed) {
    for (    RelativePoint p : container.getProtectedArea()) {
      ShortPoint2D abs=p.calculatePoint(start);
      objects[abs.x][abs.y]=protector;
      undoDelta.removeObject(abs.x,abs.y);
    }
    objects[x][y]=container;
    undoDelta.removeObject(x,y);
  }
}