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.
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