/**
   * The "base64" base encoding specified by <a
   * href="http://tools.ietf.org/html/rfc4648#section-4">RFC 4648 section 4</a>, Base 64 Encoding.
   * (This is the same as the base 64 encoding from <a
   * href="http://tools.ietf.org/html/rfc3548#section-3">RFC 3548</a>.)
   *
   * <p>The character {@code '='} is used for padding, but can be {@linkplain #omitPadding()

   *
   * <p>If you are designing a new system that needs HMAC, prefer {@link #hmacSha256} or other
   * future-proof algorithms <a
   * href="https://datatracker.ietf.org/doc/html/rfc6151#section-2.3">over {@code hmacMd5}</a>.
   *
   * @param key the secret key
   * @throws IllegalArgumentException if the given key is inappropriate for initializing this MAC
   * @since 20.0
   */

   * elements.
   *
   * <p>For streams with defined encounter order (as defined in the Ordering section of the {@link
   * java.util.stream} Javadoc), that order is preserved, but entries are <a
   * href="ImmutableMultimap.html#iteration">grouped by key</a>.
   *
   * <p>Example:
   *
   * <pre>{@code
   * static final Multimap<Character, String> FIRST_LETTER_MULTIMAP =
   *     Stream.of("banana", "apple", "carrot", "asparagus", "cherry")

  @Override
  @CheckForNull
  public abstract V get(@CheckForNull Object key);

  /**
   * {@inheritDoc}
   *
   * <p>See <a
   * href="https://developer.android.com/reference/java/util/Map.html#getOrDefault%28java.lang.Object,%20V%29">{@code
   * Map.getOrDefault}</a>.
   *
   * @since 23.5 (but since 21.0 in the JRE <a
   *     href="https://github.com/google/guava#guava-google-core-libraries-for-java">flavor</a>).

 * {@linkplain #close closed}. This is intended to approximately emulate the behavior of Java 7's <a
 * href="http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html"
 * >try-with-resources</a> statement in JDK6-compatible code. Running on Java 7, code using this
 * should be approximately equivalent in behavior to the same code written with try-with-resources.

 * powerful advantage. Although Java offers certain immutable collection factory methods, such as
 * {@link Collections#singleton(Object)} and <a
 * href="https://docs.oracle.com/javase/9/docs/api/java/util/Set.html#immutable">{@code Set.of}</a>,
 * we recommend using <i>these</i> classes instead for this reason (as well as for consistency).
 *
 * <h4>Creation</h4>
 *

   * elements.
   *
   * <p>For streams with defined encounter order (as defined in the Ordering section of the {@link
   * java.util.stream} Javadoc), that order is preserved, but entries are <a
   * href="ImmutableMultimap.html#iteration">grouped by key</a>.
   *
   * <p>Example:
   *
   * <pre>{@code
   * static final Multimap<Character, String> FIRST_LETTER_MULTIMAP =
   *     Stream.of("banana", "apple", "carrot", "asparagus", "cherry")

 * powerful advantage. Although Java offers certain immutable collection factory methods, such as
 * {@link Collections#singleton(Object)} and <a
 * href="https://docs.oracle.com/javase/9/docs/api/java/util/Set.html#immutable">{@code Set.of}</a>,
 * we recommend using <i>these</i> classes instead for this reason (as well as for consistency).
 *
 * <h4>Creation</h4>
 *

  /**
   * The HTTP <a href="http://html.spec.whatwg.org/multipage/semantics.html#hyperlink-auditing">
   * {@code Ping-From}</a> header field name.
   *
   * @since 19.0
   */
  public static final String PING_FROM = "Ping-From";
  /**
   * The HTTP <a href="http://html.spec.whatwg.org/multipage/semantics.html#hyperlink-auditing">
   * {@code Ping-To}</a> header field name.
   *

import static com.google.common.net.MediaType.ANY_TEXT_TYPE;
import static com.google.common.net.MediaType.ANY_TYPE;
import static com.google.common.net.MediaType.ANY_VIDEO_TYPE;
import static com.google.common.net.MediaType.HTML_UTF_8;
import static com.google.common.net.MediaType.JPEG;
import static com.google.common.net.MediaType.PLAIN_TEXT_UTF_8;
import static com.google.common.truth.Truth.assertThat;
import static java.lang.reflect.Modifier.isFinal;