* with the directionality of this graph.
   */
  protected final void validateEndpoints(EndpointPair<?> endpoints) {
    checkNotNull(endpoints);
    checkArgument(isOrderingCompatible(endpoints), ENDPOINTS_MISMATCH);
  }

  /**
   * Returns {@code true} iff {@code endpoints}' ordering is compatible with the directionality of
   * this graph.
   */

   * with the directionality of this graph.
   */
  protected final void validateEndpoints(EndpointPair<?> endpoints) {
    checkNotNull(endpoints);
    checkArgument(isOrderingCompatible(endpoints), ENDPOINTS_MISMATCH);
  }

  /**
   * Returns {@code true} iff {@code endpoints}' ordering is compatible with the directionality of
   * this graph.
   */

  static final String EDGE_ALREADY_EXISTS = "Edge %s already exists in the graph.";
  static final String ENDPOINTS_MISMATCH =
      "Mismatch: endpoints' ordering is not compatible with directionality of the graph";

  /** Singleton edge value for {@link Graph} implementations backed by {@link ValueGraph}s. */
  enum Presence {
    EDGE_EXISTS
  }

  static final String EDGE_ALREADY_EXISTS = "Edge %s already exists in the graph.";
  static final String ENDPOINTS_MISMATCH =
      "Mismatch: endpoints' ordering is not compatible with directionality of the graph";

  /** Singleton edge value for {@link Graph} implementations backed by {@link ValueGraph}s. */
  enum Presence {
    EDGE_EXISTS
  }

// Today, the only supported operator is "LessThan". This may change in the future,
// for example if "consumed" (as opposed to "available") type signals are added.
// In both cases the directionality of the threshold is implicit to the signal type
// (for a given signal, the decision to evict will be made when crossing the threshold
// from either above or below, never both). There is thus no reason to expose the

    }
    return hasEdgeConnecting(endpoints.nodeU(), endpoints.nodeV());
  }

  /**
   * Throws an IllegalArgumentException if the ordering of {@code endpoints} is not compatible with
   * the directionality of this graph.
   */
  protected final void validateEndpoints(EndpointPair<?> endpoints) {
    checkNotNull(endpoints);
    checkArgument(isOrderingCompatible(endpoints), ENDPOINTS_MISMATCH);
  }

    }
    return hasEdgeConnecting(endpoints.nodeU(), endpoints.nodeV());
  }

  /**
   * Throws an IllegalArgumentException if the ordering of {@code endpoints} is not compatible with
   * the directionality of this graph.
   */
  protected final void validateEndpoints(EndpointPair<?> endpoints) {
    checkNotNull(endpoints);
    checkArgument(isOrderingCompatible(endpoints), ENDPOINTS_MISMATCH);
  }

				// inexactly unifying channel type remains assignable (go.dev/issue/62157).
				//
				// If we have multiple defined channel types, they are either identical or we
				// have assignment conflicts, so we can ignore directionality in this case.
				//
				// If we have defined and literal channel types, a defined type wins to avoid
				// order dependencies.
				if mode&exact == 0 {
					switch {
					case xn:

				// inexactly unifying channel type remains assignable (go.dev/issue/62157).
				//
				// If we have multiple defined channel types, they are either identical or we
				// have assignment conflicts, so we can ignore directionality in this case.
				//
				// If we have defined and literal channel types, a defined type wins to avoid
				// order dependencies.
				if mode&exact == 0 {
					switch {
					case xn:

//
// The fundamental key to this design is the bi-directional "pointer" between
// PersistentVolumes (PVs) and PersistentVolumeClaims (PVCs), which is
// represented here as pvc.Spec.VolumeName and pv.Spec.ClaimRef. The bi-
// directionality is complicated to manage in a transactionless system, but
// without it we can't ensure sane behavior in the face of different forms of
// trouble. For example, a rogue HA controller instance could end up racing