Program: 63911
Project: 63911
Buggy source:
/** 
 * Execute <tt>DELETE</tt> operation on the database
 * @param xrService parent <code>XRService</code> that owns this <code>Operation</code>
 * @param invocation contains runtime argument values to be bound to the list of{@link Parameter}'s.
 * @return  result - can be <code>null</code> if the underlying <tt>DELETE</tt> operation on thedatabase does not return a value
 * @see  {@link Operation}
 */
@SuppressWarnings("String_Node_Str") @Override public Object invoke(XRServiceAdapter xrService,Invocation invocation){
  DatabaseQuery query=classDescriptor.getQueryManager().getQuery(PK_QUERYNAME + UNDERSCORE_STR + descriptorName+ TYPE_STR);
  if (query instanceof JPAQuery) {
    query=((JPAQuery)query).processSQLQuery(xrService.getORSession().getActiveSession());
  }
  UnitOfWork uow=xrService.getORSession().acquireUnitOfWork();
  Object toBeDeleted;
  if (query.getArguments().size() == 0) {
    int idx=0;
    for (    Parameter param : getParameters()) {
      query.addArgument(Integer.toString(++idx),Util.SCHEMA_2_CLASS.get(param.getType()));
      query.addArgumentValue(invocation.getParameter(param.getName()));
    }
    toBeDeleted=uow.executeQuery(query);
  }
 else {
    List queryArguments=query.getArguments();
    int queryArgumentsSize=queryArguments.size();
    Vector executeArguments=new NonSynchronizedVector();
    for (int i=0; i < queryArgumentsSize; i++) {
      String argName=(String)queryArguments.get(i);
      executeArguments.add(invocation.getParameter(argName));
    }
    toBeDeleted=uow.executeQuery(query,executeArguments);
  }
  if (!isCollection() && toBeDeleted instanceof Vector) {
    if (((Vector)toBeDeleted).isEmpty()) {
      toBeDeleted=null;
    }
 else {
      toBeDeleted=((Vector)toBeDeleted).firstElement();
    }
  }
  if (toBeDeleted != null) {
    uow.deleteObject(toBeDeleted);
    uow.commit();
  }
  return null;
}

Fixed version (ground truth):
/** 
 * Execute <tt>DELETE</tt> operation on the database
 * @param xrService parent <code>XRService</code> that owns this <code>Operation</code>
 * @param invocation contains runtime argument values to be bound to the list of{@link Parameter}'s.
 * @return  result - can be <code>null</code> if the underlying <tt>DELETE</tt> operation on thedatabase does not return a value
 * @see  {@link Operation}
 */
@SuppressWarnings("String_Node_Str") @Override public Object invoke(XRServiceAdapter xrService,Invocation invocation){
  DatabaseQuery query=classDescriptor.getQueryManager().getQuery(getFindByPKQuery());
  if (query instanceof JPAQuery) {
    query=((JPAQuery)query).processSQLQuery(xrService.getORSession().getActiveSession());
  }
  UnitOfWork uow=xrService.getORSession().acquireUnitOfWork();
  Object toBeDeleted;
  if (query.getArguments().size() == 0) {
    int idx=0;
    for (    Parameter param : getParameters()) {
      query.addArgument(Integer.toString(++idx),Util.SCHEMA_2_CLASS.get(param.getType()));
      query.addArgumentValue(invocation.getParameter(param.getName()));
    }
    toBeDeleted=uow.executeQuery(query);
  }
 else {
    List queryArguments=query.getArguments();
    int queryArgumentsSize=queryArguments.size();
    Vector executeArguments=new NonSynchronizedVector();
    for (int i=0; i < queryArgumentsSize; i++) {
      String argName=(String)queryArguments.get(i);
      executeArguments.add(invocation.getParameter(argName));
    }
    toBeDeleted=uow.executeQuery(query,executeArguments);
  }
  if (!isCollection() && toBeDeleted instanceof Vector) {
    if (((Vector)toBeDeleted).isEmpty()) {
      toBeDeleted=null;
    }
 else {
      toBeDeleted=((Vector)toBeDeleted).firstElement();
    }
  }
  if (toBeDeleted != null) {
    uow.deleteObject(toBeDeleted);
    uow.commit();
  }
  return null;
}