There are some extra features to handle security apart from the ones covered in the [Tutorial - User Guide: Security](../../tutorial/security/index.md).

/// tip

The next sections are **not necessarily "advanced"**.

And it's possible that for your use case, the solution is in one of them.

///

## Read the Tutorial first { #read-the-tutorial-first }

In the next sections you will see other options, configurations, and additional features.

/// tip

The next sections are **not necessarily "advanced"**.

And it's possible that for your use case, the solution is in one of them.

///

## Read the Tutorial first { #read-the-tutorial-first }

@GwtCompatible
public final class Runnables {
  /*
   * If we inline this, it's not longer a singleton under Android (at least under the Marshmallow
   * version that we're testing under) or J2CL.
   *
   * That's not necessarily a real-world problem, but it does break our tests.
   */
  @SuppressWarnings({"InlineLambdaConstant", "UnnecessaryLambda"})
  private static final Runnable EMPTY_RUNNABLE = () -> {};

/// warning

Extra keys passed to `Field` will also be present in the resulting OpenAPI schema for your application.
As these keys may not necessarily be part of the OpenAPI specification, some OpenAPI tools, for example [the OpenAPI validator](https://validator.swagger.io/), may not work with your generated schema.

///

## Recap { #recap }

This provider might be charging you per request, and calling it might take some extra time than if you had a fixed mock user for tests.

You probably want to test the external provider once, but not necessarily call it for every test that runs.

In this case, you can override the dependency that calls that provider, and use a custom dependency that returns a mock user, only for your tests.

       */
      return;
    }

    /*
     * Only under Windows (or hypothetically when running with some other non-POSIX, ACL-based
     * filesystem) does our prod code look up the username. Thus, this test doesn't necessarily test
     * anything interesting under most environments. Still, we can run it (except for Android, at
     * least old versions), so we mostly do. This is useful because we don't actually run our CI on

import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A skeleton {@code Multimap} implementation, not necessarily in terms of a {@code Map}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
abstract class AbstractMultimap<K extends @Nullable Object, V extends @Nullable Object>
    implements Multimap<K, V> {
  @Override

   * from least to greatest. If there are fewer than {@code k} elements present, all will be
   * included.
   *
   * <p>The implementation does not necessarily use a <i>stable</i> sorting algorithm; when multiple
   * elements are equivalent, it is undefined which will come first.
   *
   * <p><b>Java 8+ users:</b> Use {@code Streams.stream(iterable).collect(Comparators.least(k,

   * from least to greatest. If there are fewer than {@code k} elements present, all will be
   * included.
   *
   * <p>The implementation does not necessarily use a <i>stable</i> sorting algorithm; when multiple
   * elements are equivalent, it is undefined which will come first.
   *
   * <p><b>Java 8+ users:</b> Use {@code Streams.stream(iterable).collect(Comparators.least(k,

   * The order of the elements in the element set is unspecified.
   *
   * <p>If the element set supports any removal operations, these necessarily cause <b>all</b>
   * occurrences of the removed element(s) to be removed from the multiset. Implementations are not
   * expected to support the add operations, although this is possible.
   *