/guava/guava/src/com/google/common/collect/ForwardingSortedSet.java
return delegate ( ) .headSet ( toElement ) ;
@ParametricNullness public E first() { return delegate().first(); } @Override public SortedSet<E> headSet(@ParametricNullness E toElement) { <extra_id_0> } @Override @ParametricNullness public E last() { return delegate().last(); }