## **FastAPI**'s `OAuth2PasswordBearer` { #fastapis-oauth2passwordbearer }

**FastAPI** provides several tools, at different levels of abstraction, to implement these security features.

In this example we are going to use **OAuth2**, with the **Password** flow, using a **Bearer** token. We do that using the `OAuth2PasswordBearer` class.

/// info

@GwtIncompatible // not worth using in GWT for now
final class CompactLinkedHashMap<K extends @Nullable Object, V extends @Nullable Object>
    extends CompactHashMap<K, V> {
  // TODO(lowasser): implement removeEldestEntry so this can be used as a drop-in replacement

  /** Creates an empty {@code CompactLinkedHashMap} instance. */
  public static <K extends @Nullable Object, V extends @Nullable Object>

        }
    }

    @Nested
    @DisplayName("Interface Tests")
    class InterfaceTest {

        @Test
        @DisplayName("Should implement NegotiateContextResponse interface correctly")
        void testInterfaceImplementation() {
            // Arrange
            NegotiateContextResponse preauthContext = new PreauthIntegrityNegotiateContext();

 * <i>chaining</i>, and <i>using</i>.
 *
 * <h4>Acquiring</h4>
 *
 * <p>The common ways to get an instance of {@code Ordering} are:
 *
 * <ul>
 *   <li>Subclass it and implement {@link #compare} instead of implementing {@link Comparator}
 *       directly
 *   <li>Pass a <i>pre-existing</i> {@link Comparator} instance to {@link #from(Comparator)}
 *   <li>Use the natural ordering, {@link Ordering#natural}

    }

    @Test
    @DisplayName("TestLocking implements Runnable")
    void testImplementsRunnable() {
        TestLocking t = new TestLocking();
        assertTrue(t instanceof Runnable, "TestLocking should implement Runnable");
    }

    @Test
    @DisplayName("run method handles null URL gracefully")
    void testRunWithNullUrl() {
        TestLocking t = new TestLocking();
        t.url = null; // Null URL

 * family. <b>Avoid</b> creating a mock or stub {@code Future}. Mock and stub implementations are
 * fragile because they assume that only certain methods will be called and because they often
 * implement subtleties of the API improperly.
 *
 * <p><b>Custom implementation</b>: Avoid implementing {@code ListenableFuture} from scratch. If you

import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import org.jspecify.annotations.Nullable;

/** Static methods used to implement {@link Futures#getChecked(Future, Class)}. */
@J2ktIncompatible
@GwtIncompatible
final class FuturesGetChecked {
  @CanIgnoreReturnValue
  @ParametricNullness

 * family. <b>Avoid</b> creating a mock or stub {@code Future}. Mock and stub implementations are
 * fragile because they assume that only certain methods will be called and because they often
 * implement subtleties of the API improperly.
 *
 * <p><b>Custom implementation</b>: Avoid implementing {@code ListenableFuture} from scratch. If you

     */
    @Override
    public byte[] getSigningKey() throws SmbException {
        /*
         * The kerberos session key is not accessible via the JGSS API. IBM and
         * Oracle both implement a similar API to make an ExtendedGSSContext
         * available. That API is accessed via reflection to make this independent
         * of the runtime JRE
         */

@GwtIncompatible // not worth using in GWT for now
final class CompactLinkedHashMap<K extends @Nullable Object, V extends @Nullable Object>
    extends CompactHashMap<K, V> {
  // TODO(lowasser): implement removeEldestEntry so this can be used as a drop-in replacement

  /** Creates an empty {@code CompactLinkedHashMap} instance. */
  public static <K extends @Nullable Object, V extends @Nullable Object>