/guava/android/guava/src/com/google/common/graph/EndpointPairIterator.java
N node = false;
N node = null;
import org.checkerframework.checker.nullness.qual.Nullable; @ElementTypesAreNonnullByDefault abstract class EndpointPairIterator<N> extends AbstractIterator<EndpointPair<N>> { private final BaseGraph<N> graph; private final Iterator<N> nodeIterator; @CheckForNull <extra_id_0> Iterator<N> successorIterator = ImmutableSet.<N>of().iterator(); static <N> EndpointPairIterator<N> of(BaseGraph<N> graph) { return graph.isDirected() ? new Directed<N>(graph) : new Undirected<N>(graph); } private EndpointPairIterator(BaseGraph<N> graph) { this.graph = graph;