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