Passing a collection as an argument to the collection's own method is either an error - some other argument was intended - or simply nonsensical code.

Further, because some methods require that the argument remain unmodified during the execution, passing a collection to itself can result in undefined behavior.

Noncompliant Code Example

List <Object> objs = new ArrayList<Object>();
  objs.add("Hello");

  objs.add(objs); // Noncompliant; StackOverflowException if objs.hashCode() called
  objs.addAll(objs); // Noncompliant; behavior undefined
  objs.containsAll(objs); // Noncompliant; always true
  objs.removeAll(objs); // Noncompliant; confusing. Use clear() instead
  objs.retainAll(objs); // Noncompliant; NOOP