/guava/android/guava/src/com/google/common/collect/Synchronized.java
if ( ( entrySet) == null) {   entrySet = typePreservingSet( delegate( ).entrySet( ) , mutex) ; }
[Delete]
} } @Override public Set<K> keySet() { synchronized (mutex) { if (keySet == null) { <extra_id_0> } return keySet; } } @Override @CheckForNull