network.addNode(gen.nextInt(NODE_POOL_SIZE));
      }
      ArrayList<Integer> nodeList = new ArrayList<>(network.nodes());
      for (int i = 0; i < NUM_EDGES; ++i) {
        // Parallel edges are allowed, so this should always succeed.
        assertThat(
                network.addEdge(
                    getRandomElement(nodeList, gen), getRandomElement(nodeList, gen), new Object()))
            .isTrue();
      }

import java.util.Iterator;
import org.jspecify.annotations.NonNull;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A simplistic collection which implements only the bare minimum allowed by the spec, and throws
 * exceptions whenever it can.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@NullMarked
public class MinimalCollection<E extends @Nullable Object> extends AbstractCollection<E> {

@NullUnmarked
final class TestUtil {
  static final String ERROR_ELEMENT_NOT_IN_GRAPH = "not an element of this graph";
  static final String ERROR_NODE_NOT_IN_GRAPH =
      "Should not be allowed to pass a node that is not an element of the graph.";
  static final String ERROR_ELEMENT_REMOVED = "used to generate this set";
  private static final String NODE_STRING = "Node";
  private static final String EDGE_STRING = "Edge";

    assertThrows(
        UnsupportedOperationException.class,
        () ->
            getMap()
                .computeIfAbsent(
                    k3(),
                    k -> {
                      // allowed to be called
                      assertEquals(k3(), k);
                      return v3();
                    }));
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)

   * @see java.util.Collection the definition of general-purpose collections.
   */
  GENERAL_PURPOSE(SUPPORTS_ADD, SUPPORTS_REMOVE, SUPPORTS_ITERATOR_REMOVE),

  /** Features supported by collections where only removal is allowed. */
  REMOVE_OPERATIONS(SUPPORTS_REMOVE, SUPPORTS_ITERATOR_REMOVE),

  SERIALIZABLE,
  SERIALIZABLE_INCLUDING_VIEWS(SERIALIZABLE),

  SUBSET_VIEW,
  DESCENDING_VIEW,

  /**

          + "that allows parallel edges, call allowsParallelEdges(true) on the Builder.";
  static final String SELF_LOOPS_NOT_ALLOWED =
      "Cannot add self-loop edge on node %s, as self-loops are not allowed. To construct a graph "
          + "that allows self-loops, call allowsSelfLoops(true) on the Builder.";
  static final String NOT_AVAILABLE_ON_UNDIRECTED =

          assertUnescaped(xmlEscaper, ch);
        }
      } else {
        // and everything else is replaced with FFFD.
        assertEscaping(xmlEscaper, "\uFFFD", ch);
      }
    }

    // Test _all_ allowed characters (including surrogate values).
    for (char ch = 0x20; ch <= 0xFFFD; ch++) {
      // There are a small number of cases to consider, so just do it manually.
      if (ch == '&') {

    #  The handling type when undefined classification is found.
    #
    #   EXCEPTION - throws exception when found
    #   LOGGING   - logging only when found (exception if ReplaceSchema)
    #   ALLOWED   - no action
    #
    #; classificationUndefinedHandlingType = LOGGING
    # - - - - - - - - - -/

    # /- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

   * @see java.util.Collection the definition of general-purpose collections.
   */
  GENERAL_PURPOSE(SUPPORTS_ADD, SUPPORTS_REMOVE, SUPPORTS_ITERATOR_REMOVE),

  /** Features supported by collections where only removal is allowed. */
  REMOVE_OPERATIONS(SUPPORTS_REMOVE, SUPPORTS_ITERATOR_REMOVE),

  SERIALIZABLE,
  SERIALIZABLE_INCLUDING_VIEWS(SERIALIZABLE),

  SUBSET_VIEW,
  DESCENDING_VIEW,

  /**

  }

  // ----------------------------------------------------------------
  // Test that interrupts result in RuntimeException, not InterruptedException.
  // Trickier than it looks, because runFinalization swallows interrupts.
  // ----------------------------------------------------------------

  class Interruptenator extends Thread {
    final AtomicBoolean shutdown;

    Interruptenator(Thread interruptee) {