Program: 185455
Project: 185455
Buggy source:
@Override protected void setUpLinkedMode(IDocument document,char closingCharacter){
  if (getTextViewer() != null) {
    try {
      int baseOffset=getReplacementOffset();
      LinkedModeModel model=new LinkedModeModel();
      for (int i=0; i < fPositions.size(); i+=1) {
        Position position=fPositions.get(i);
        position.setOffset(baseOffset + position.getOffset());
        LinkedPositionGroup group=new LinkedPositionGroup();
        if (fProposals.size() <= i || fProposals.get(i).length < 2) {
          group.addPosition(new LinkedPosition(document,position.getOffset(),position.getLength(),LinkedPositionGroup.NO_STOP));
        }
 else {
          ensurePositionCategoryInstalled(document,model);
          document.addPosition(fPositionCategory,position);
          group.addPosition(new ProposalPosition(document,position.getOffset(),position.getLength(),LinkedPositionGroup.NO_STOP,fProposals.get(i)));
        }
        model.addGroup(group);
      }
      JavaEditor editor=getJavaEditor();
      if (editor != null) {
        model.addLinkingListener(new EditorHighlightingSynchronizer(editor));
      }
      model.forceInstall();
      LinkedModeUI ui=new EditorLinkedModeUI(model,getTextViewer());
      ui.setCyclingMode(LinkedModeUI.CYCLE_NEVER);
      ui.setDoContextInfo(true);
      ui.setExitPolicy(new ExitPolicy(closingCharacter,document));
      ui.setExitPosition(getTextViewer(),baseOffset + getCursorPosition(),0,Integer.MAX_VALUE);
      ui.enter();
    }
 catch (    BadLocationException|BadPositionCategoryException e) {
      GroovyContentAssist.logError(e);
    }
  }
}

Fixed version (ground truth):
@Override protected void setUpLinkedMode(IDocument document,char closingCharacter){
  if (getTextViewer() != null) {
    try {
      int baseOffset=getReplacementOffset();
      LinkedModeModel model=new LinkedModeModel();
      if (fPositions == null) {
        LinkedPositionGroup group=new LinkedPositionGroup();
        group.addPosition(new LinkedPosition(document,baseOffset + fContextInformationPosition,0));
        model.addGroup(group);
      }
 else {
        for (int i=0, n=fPositions.size(); i < n; i+=1) {
          Position position=fPositions.get(i);
          position.setOffset(baseOffset + position.getOffset());
          LinkedPositionGroup group=new LinkedPositionGroup();
          if (fProposals.size() <= i || fProposals.get(i).length <= 1) {
            group.addPosition(new LinkedPosition(document,position.getOffset(),position.getLength(),LinkedPositionGroup.NO_STOP));
          }
 else {
            ensurePositionCategoryInstalled(document,model);
            document.addPosition(fPositionCategory,position);
            group.addPosition(new ProposalPosition(document,position.getOffset(),position.getLength(),LinkedPositionGroup.NO_STOP,fProposals.get(i)));
          }
          model.addGroup(group);
        }
      }
      JavaEditor editor=getJavaEditor();
      if (editor != null) {
        model.addLinkingListener(new EditorHighlightingSynchronizer(editor));
      }
      model.forceInstall();
      LinkedModeUI ui=new EditorLinkedModeUI(model,getTextViewer());
      ui.setCyclingMode(LinkedModeUI.CYCLE_NEVER);
      ui.setDoContextInfo(true);
      ui.setExitPolicy(new ExitPolicy(closingCharacter,document));
      ui.setExitPosition(getTextViewer(),baseOffset + getCursorPosition(),0,Integer.MAX_VALUE);
      ui.enter();
    }
 catch (    BadLocationException|BadPositionCategoryException e) {
      GroovyContentAssist.logError(e);
    }
  }
}