/guava/android/guava/src/com/google/common/graph/EndpointPair.java
this.nodeV = checkNotNull ( nodeV ) ;
@ElementTypesAreNonnullByDefault public abstract class EndpointPair<N> implements Iterable<N> { private final N nodeU; private final N nodeV; private EndpointPair(N nodeU, N nodeV) { this.nodeU = checkNotNull(nodeU); <extra_id_0> } public static <N> EndpointPair<N> ordered(N source, N target) { return new Ordered<>(source, target); } public static <N> EndpointPair<N> unordered(N nodeU, N nodeV) { return new Unordered<>(nodeV, nodeU);