new SecretKeySpec("secret key".getBytes(UTF_8), "HmacSHA256");
  private static final SecretKey SHA512_KEY =
      new SecretKeySpec("secret key".getBytes(UTF_8), "HmacSHA512");

  // From http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Mac
  private static final ImmutableTable<String, SecretKey, HashFunction> ALGORITHMS =
      new ImmutableTable.Builder<String, SecretKey, HashFunction>()

   * {@link java.io.PrintWriter#format PrintWriter.format}, and related methods. These support the
   * full range of <a
   * href="https://docs.oracle.com/javase/9/docs/api/java/util/Formatter.html#syntax">format
   * specifiers</a>, and alert you to usage errors by throwing {@link
   * java.util.IllegalFormatException}.
   *

                  /**
                   * Returns a Multiset that throws an exception on any attempt to use a method not
                   * specifically authorized by the elementSet() or hashCode() docs.
                   */
                  @Override
                  protected Set<String> create(String[] elements) {
                    final Multiset<String> inner =

   *     <ul>
   *       <li>For security:
   *           {@link Hashing#sha256} or a higher-level API.
   *       <li>For speed: {@link Hashing#goodFastHash}, though see its docs for caveats.
   *     </ul>
   */
  @Deprecated
  public static HashFunction md5() {
    return Md5Holder.MD5;
  }

  private static class Md5Holder {

   * result of this comparison chain has not already been determined.
   *
   * <p>This method is declared to accept any 2 {@code Comparable} objects, even if they are not <a
   * href="https://docs.oracle.com/javase/tutorial/collections/interfaces/order.html">mutually
   * comparable</a>. If you pass objects that are not mutually comparable, this method may throw an

                <!-- https://github.com/google/error-prone/blob/f8e33bc460be82ab22256a7ef8b979d7a2cacaba/docs/installation.md#jdk-16 -->
                <!-- TODO(cpovirk): Use .mvn/jvm.config instead (per
                     https://errorprone.info/docs/installation#maven) if it can
                     be made not to interfere with JDK8 or if we stop building
                     with JDK8. -->

   * {@link java.io.PrintWriter#format PrintWriter.format}, and related methods. These support the
   * full range of <a
   * href="https://docs.oracle.com/javase/9/docs/api/java/util/Formatter.html#syntax">format
   * specifiers</a>, and alert you to usage errors by throwing {@link
   * java.util.IllegalFormatException}.
   *

import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Static convenience methods that serve the same purpose as Java language <a
 * href="https://docs.oracle.com/javase/8/docs/technotes/guides/language/assert.html">assertions</a>,
 * except that they are always enabled. These methods should be used instead of Java assertions
 * whenever there is a chance the check may fail "in real life". Example:

 *       not look for classes in the <i>module path</i>.
 *   <li>It understands only {@code file:} URLs. This means that it does not understand <a
 *       href="https://openjdk.java.net/jeps/220">{@code jrt:/} URLs</a>, among <a
 *       href="https://github.com/classgraph/classgraph/wiki/Classpath-specification-mechanisms">others</a>.

   * mod(7, 4) == 3
   * mod(-7, 4) == 1
   * mod(-1, 4) == 3
   * mod(-8, 4) == 0
   * mod(8, 4) == 0
   * }</pre>
   *
   * @throws ArithmeticException if {@code m <= 0}
   * @see <a href="http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.17.3">
   *     Remainder Operator</a>
   */
  @GwtIncompatible // TODO
  public static int mod(long x, int m) {