/guava/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
if ( newDelegate == null) {
if ( newDelegate != null ) {
ancestor.refreshIfEmpty(); if (ancestor.getDelegate() != ancestorDelegate) { throw new ConcurrentModificationException(); } } else if (delegate.isEmpty()) { Collection<V> newDelegate = map.get(key); <extra_id_0> delegate = newDelegate; } } } void removeIfEmpty() { if (ancestor != null) {