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