* <p>If this graph is directed, {@code endpoints} must be ordered.
   *
   * <p><b>{@code edge} must be unique to this graph</b>, just as a {@code Map} key must be. It must
   * also be non-null.
   *
   * <p>If either or both endpoints are not already present in this graph, this method will silently
   * {@link #addNode(Object) add} each missing endpoint to the graph.
   *

import com.google.common.collect.ImmutableList;
import com.google.errorprone.annotations.CanIgnoreReturnValue;

/**
 * Standard implementation of {@link MutableNetwork} that supports both directed and undirected
 * graphs. Instances of this class should be constructed with {@link NetworkBuilder}.
 *
 * <p>Time complexities for mutation methods are all O(1) except for {@code removeNode(N node)},

   * @return the value that was previously associated with the key, or {@code null} if there was no
   *     previous entry. (If the bimap contains null values, then {@code forcePut}, like {@code
   *     put}, returns {@code null} both if the key is absent and if it is present with a null
   *     value.)
   */
  @CanIgnoreReturnValue
  @Nullable V forcePut(@ParametricNullness K key, @ParametricNullness V value);

  // Bulk Operations

  /**

  }

  /**
   * This is an extraordinary test case. Here's what it's trying to simulate.
   * - 2 requests happen concurrently to a host that can be coalesced onto a single connection.
   * - Both request discover no existing connection. They both make a connection.
   * - The first request "wins the race".
   * - The second request discovers it "lost the race" and closes the connection it just opened.

   * @throws NullPointerException if both {@code first} and {@code second} are null
   * @since 18.0 (since 3.0 as {@code Objects.firstNonNull()}).
   */
  public static <T> T firstNonNull(@Nullable T first, @Nullable T second) {
    if (first != null) {
      return first;
    }
    if (second != null) {
      return second;
    }
    throw new NullPointerException("Both parameters are null");
  }

  /**

        if (isEmpty(s1)) {
            return false;
        }
        return s1.indexOf(s2) >= 0;
    }

    /**
     * Returns whether two strings are equal. If both are null, returns <code>true</code>.
     *
     * @param target1
     *            the first string
     * @param target2
     *            the second string

        // Get another region - should potentially reuse from pool
        RdmaMemoryRegion region2 = bufferManager.getSendRegion(1024);
        assertNotNull(region2);

        // Both regions should be valid
        assertTrue(region1.isValid() || !region1.isValid()); // Either state is OK after release
        assertTrue(region2.isValid(), "New region should be valid");
    }

    // GET /api/admin/duplicatehost/settings
    // PUT /api/admin/duplicatehost/settings
    /**
     * Returns list of duplicate host settings.
     * Supports both GET and PUT requests for retrieving paginated duplicate host configurations.
     *
     * @param body search parameters for filtering and pagination

* for **output** it will be **required** (and possibly `None`, or in JSON terms, `null`)

### Model for Output in Docs { #model-for-output-in-docs }

You can check the output model in the docs too, **both** `name` and `description` are marked as **required** with a **red asterisk**:

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image03.png">
</div>

import java.util.EnumMap;
import java.util.Map;

/**
 * A {@code BiMap} backed by two {@code EnumMap} instances. Null keys and values are not permitted.
 * An {@code EnumBiMap} and its inverse are both serializable.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap}</a>.
 *
 * @author Mike Bostock
 * @since 2.0
 */