* ClassLoader that loaded that class from later being garbage-collected. If anything continues
   * to reference the FinalizableReferenceQueue class then its ClassLoader cannot be
   * garbage-collected, even if there are no more instances of FinalizableReferenceQueue itself.
   * The code in FinalizableReferenceQueue goes to considerable trouble to ensure that there are
   * no such references and the tests here check that that trouble has not been in vain.
   *

  }

  Optional() {}

  /**
   * Returns {@code true} if this holder contains a (non-null) instance.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> no differences.
   */
  public abstract boolean isPresent();

  /**
   * Returns the contained instance, which must be present. If the instance might be absent, use
   * {@link #or(Object)} or {@link #orNull} instead.
   *

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.graph.Graphs.checkNonNegative;

import com.google.errorprone.annotations.CanIgnoreReturnValue;

/**
 * A builder for constructing instances of {@link MutableValueGraph} or {@link ImmutableValueGraph}
 * with user-defined properties.
 *
 * <p>A {@code ValueGraph} built by this class has the following default properties:
 *
 * <ul>

    @Override
    public Builder<E> addAll(Iterable<? extends E> elements) {
      checkNotNull(elements);
      if (elements instanceof Collection) {
        Collection<?> collection = (Collection<?>) elements;
        ensureRoomFor(collection.size());
        if (collection instanceof ImmutableCollection) {
          ImmutableCollection<?> immutableCollection = (ImmutableCollection<?>) collection;

 * <ul>
 *   <li>Call {@link #clearCredentials()} after authentication is complete to clear sensitive data from memory</li>
 *   <li>Avoid logging instances of this class as it may expose credentials</li>
 *   <li>Consider using external secret management systems for credential storage in production</li>
 * </ul>
 *
 * @author shinsuke
 */
public class FtpAuthentication {

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import org.jspecify.annotations.Nullable;

/**
 * Standard implementation of {@link MutableValueGraph} that supports both directed and undirected
 * graphs. Instances of this class should be constructed with {@link ValueGraphBuilder}.
 *
 * <p>Time complexities for mutation methods are all O(1) except for {@code removeNode(N node)},

///

/// note | Technical Details

When you import `Query`, `Path` and others from `fastapi`, they are actually functions.

That when called, return instances of classes of the same name.

So, you import `Query`, which is a function. And when you call it, it returns an instance of a class also named `Query`.

These functions are there (instead of just using the classes directly) so that your editor doesn't mark errors about their types.

import java.lang.reflect.Method;
import java.util.Map.Entry;
import java.util.Random;
import junit.framework.TestSuite;
import org.jspecify.annotations.NullUnmarked;

/**
 * A generator of {@code TestSuite} instances for testing {@code ByteSource} implementations.
 * Generates tests of all methods on a {@code ByteSource} given various inputs the source is
 * expected to contain as well as sub-suites for testing the {@code CharSource} view and {@code

 * returned.
 *
 * <p>All default instances returned by {@link #get} are generics-safe. Clients won't get type
 * errors for using {@code get(Comparator.class)} as a {@code Comparator<Foo>}, for example.
 * Immutable empty instances are returned for collection types; {@code ""} for string; {@code 0} for
 * number types; reasonable default instance for other stateless types. For mutable types, a fresh

            // Both non-null - should be same instance
            assertSame(first, second, "Second getSubject should return same cached instance as first");
        } else {
            fail("Inconsistent behavior: first=" + first + ", second=" + second);
        }

        // Third call should return the same cached Subject instance
        Subject third = auth.getSubject();