Program: 41823
Project: 41823
Buggy source:
/** 
 * Updates the viewport at (row, column) and sets it as the currently active one. The top left sub viewport is (0, 0).
 * @param row The index of the row with the viewport to be activated. Starts at 0.
 * @param column The index of the column with the viewport to be activated. Starts at 0.
 * @param centerCamera Whether the subView should center the camera or not.
 */
public void activateSubViewport(int row,int column,boolean centerCamera){
  validateCoordinates(row,column);
  Array<SubView> rowMap=subViews.get(row);
  Viewport viewport=rowMap.get(column).viewport;
  calculateSubViewportArea(row,column,subViewportArea);
  viewport.update((int)subViewportArea.width,(int)subViewportArea.height,centerCamera);
  float originalWorldWidth=viewport.getWorldWidth();
  float originalWorldHeight=viewport.getWorldHeight();
  if (viewport.getScreenWidth() > subViewportArea.width) {
    float offcutWidth=viewport.getScreenWidth() - subViewportArea.width;
    viewport.setScreenWidth((int)subViewportArea.width);
    viewport.setWorldWidth(viewport.getWorldWidth() - offcutWidth);
    viewport.setScreenX((int)(viewport.getScreenX() + offcutWidth / 2));
  }
  if (viewport.getScreenHeight() > subViewportArea.height) {
    float offcutHeight=viewport.getScreenHeight() - subViewportArea.height;
    viewport.setScreenHeight((int)subViewportArea.height);
    viewport.setWorldHeight(viewport.getWorldHeight() - offcutHeight);
    viewport.setScreenY((int)(viewport.getScreenY() + offcutHeight / 2));
  }
  viewport.setScreenX((int)(viewport.getScreenX() + subViewportArea.x));
  viewport.setScreenY((int)(viewport.getScreenX() + subViewportArea.y));
  viewport.apply();
  viewport.setWorldWidth(originalWorldWidth);
  viewport.setWorldHeight(originalWorldHeight);
  activeViewport=viewport;
}

Fixed version (ground truth):
/** 
 * Updates the viewport at (row, column) and sets it as the currently active one. The top left sub viewport is (0, 0).
 * @param row The index of the row with the viewport to be activated. Starts at 0.
 * @param column The index of the column with the viewport to be activated. Starts at 0.
 * @param centerCamera Whether the subView should center the camera or not.
 */
public void activateSubViewport(int row,int column,boolean centerCamera){
  validateCoordinates(row,column);
  Array<SubView> rowMap=subViews.get(row);
  Viewport viewport=rowMap.get(column).viewport;
  calculateSubViewportArea(row,column,subViewportArea);
  viewport.update((int)subViewportArea.width,(int)subViewportArea.height,centerCamera);
  float originalWorldWidth=viewport.getWorldWidth();
  float originalWorldHeight=viewport.getWorldHeight();
  if (viewport.getScreenWidth() > subViewportArea.width) {
    float offcutWidth=viewport.getScreenWidth() - subViewportArea.width;
    viewport.setScreenWidth((int)subViewportArea.width);
    viewport.setWorldWidth(viewport.getWorldWidth() - offcutWidth);
    viewport.setScreenX((int)(viewport.getScreenX() + offcutWidth / 2));
  }
  if (viewport.getScreenHeight() > subViewportArea.height) {
    float offcutHeight=viewport.getScreenHeight() - subViewportArea.height;
    viewport.setScreenHeight((int)subViewportArea.height);
    viewport.setWorldHeight(viewport.getWorldHeight() - offcutHeight);
    viewport.setScreenY((int)(viewport.getScreenY() + offcutHeight / 2));
  }
  viewport.setScreenX((int)(viewport.getScreenX() + subViewportArea.x));
  viewport.setScreenY((int)(viewport.getScreenY() + subViewportArea.y));
  viewport.apply();
  viewport.setWorldWidth(originalWorldWidth);
  viewport.setWorldHeight(originalWorldHeight);
  activeViewport=viewport;
}