* first.or(supplier)}.
   *
   * <p><b>Java 9 users:</b> use {@code java.util.Objects.requireNonNullElse(first, second)}
   * instead.
   *
   * @return {@code first} if it is non-null; otherwise {@code second} if it is non-null
   * @throws NullPointerException if both {@code first} and {@code second} are null
   * @since 18.0 (since 3.0 as {@code Objects.firstNonNull()}).
   */

    for (RoundingMode mode : ALL_ROUNDING_MODES) {
      assertThrows(IllegalArgumentException.class, () -> LongMath.log2(0L, mode));
    }
  }

  public void testLog2NegativeAlwaysThrows() {
    for (long x : NEGATIVE_LONG_CANDIDATES) {
      for (RoundingMode mode : ALL_ROUNDING_MODES) {
        assertThrows(IllegalArgumentException.class, () -> LongMath.log2(x, mode));
      }
    }
  }

  }

  /**
   * Returns a new array that prepends {@code element} to {@code array}.
   *
   * @param element the element to prepend to the front of {@code array}
   * @param array the array of elements to append
   * @return an array whose size is one larger than {@code array}, with {@code element} occupying
   *     the first position, and the elements of {@code array} occupying the remaining elements.
   */

 * <p>In addition, this class provides several static methods for converting a {@code long} to a
 * {@code String} and a {@code String} to a {@code long} that treat the {@code long} as an unsigned
 * number.
 *
 * <p>Users of these utilities must be <i>extremely careful</i> not to mix up signed and unsigned
 * {@code long} values. When possible, it is recommended that the {@link UnsignedLong} wrapper class

   * first over all the elements of {@code set1}, then over each element of {@code set2}, in order,
   * that is not contained in {@code set1}.
   *
   * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
   */

     * @return The effective repositories or {@code null} if the input was {@code null}.
     */
    List<ArtifactRepository> getEffectiveRepositories(List<ArtifactRepository> repositories);

    /**
     * Determines the mirror for the specified repository.
     *
     * @param repository The repository to determine the mirror for, must not be {@code null}.

    }

    /**
     * Set the user name which is used to setup <code>GSSContext</code>. If null
     * is set, the default user will be used which is retrieved from the first
     * TGT found in <code>Subject</code> .
     *
     * @param name
     *            the user name used to setup <code>GSSContext</code>
     */
    public void setUser(String name) {
        this.user = name;
    }

    } else {
      int k = 20;
      return BigInteger.valueOf(LongMath.factorial(k)).multiply(oldSlowFactorial(k, n));
    }
  }

  /** Returns the product of {@code n1} exclusive through {@code n2} inclusive. */
  @SuppressWarnings("UseCorrectAssertInTests") // TODO(b/345814817): Remove or convert assertion.
  private static BigInteger oldSlowFactorial(int n1, int n2) {
    assert n1 <= n2;

     *
     * @param node1 the first artifact declaration
     * @param node2 the second artifact declaration
     * @return the artifact declaration to use: <code>node1</code>; <code>node2</code>; or <code>null</code>if
     *         this conflict cannot be resolved
     * @since 3.0
     */
    ResolutionNode resolveConflict(ResolutionNode node1, ResolutionNode node2);

 * supplied by the user of the class. For example, {@code Multiset.Entry.getElement()} returns
 * {@code @ParametricNullness E}, which means:
 *
 * <ul>
 *   <li>{@code getElement} on a {@code Multiset.Entry<@NonNull String>} returns {@code @NonNull
 *       String}.
 *   <li>{@code getElement} on a {@code Multiset.Entry<@Nullable String>} returns {@code @Nullable
 *       String}.
 * </ul>
 *