*
 * Cancellation
 * ------------
 *
 * Tasks may be canceled while they are waiting to be executed, or while they are executing.
 *
 * Canceling a task that is waiting to execute prevents that upcoming execution. Canceling a task
 * that is currently executing does not impact the ongoing run, but it does prevent a recurrence
 * from being scheduled.
 *

carry prominent notices stating that You changed the files; and (c) You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and (d) If the Work includes a "NOTICE" text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices...

   * many individual lookups. Note that {@link LoadingCache#getAll} will defer to individual calls
   * to {@link LoadingCache#get} if this method is not overridden.
   *
   * @param keys the unique, non-null keys whose values should be loaded
   * @return a map from each key in {@code keys} to the value associated with that key; <b>may not
   *     contain null values</b>

    public void test_serialization() {
        // Test that the serialVersionUID is properly defined
        // This test verifies that the class can be instantiated and has the serial version UID
        ServletException servletException = new ServletException("Serialization test");
        ServletRuntimeException runtimeException = new ServletRuntimeException(servletException);

 * take advantage of the {@linkplain Futures utilities built atop the class}. The way that you will
 * create {@code ListenableFuture} instances depends on how you currently create {@code Future}
 * instances:
 *
 * <ul>
 *   <li>If you receive them from an {@code java.util.concurrent.ExecutorService}, convert that

 * take advantage of the {@linkplain Futures utilities built atop the class}. The way that you will
 * create {@code ListenableFuture} instances depends on how you currently create {@code Future}
 * instances:
 *
 * <ul>
 *   <li>If you receive them from an {@code java.util.concurrent.ExecutorService}, convert that

        // if removeAll returns true, all we really know is that at least one subscriber was
        // removed... however, barring something very strange we can assume that if at least one
        // subscriber was removed, all subscribers on listener for that event type were... after
        // all, the definition of subscribers on a particular class is totally static

import java.util.Iterator;
import java.util.NoSuchElementException;

import org.codelibs.core.exception.ClUnsupportedOperationException;
import org.codelibs.core.message.MessageFormatter;

/**
 * An {@link Iterator} that iterates through the inheritance hierarchy of a class towards its superclasses.
 * <p>
 * Usage example:
 * </p>
 *
 * <pre>
 * import static org.codelibs.core.lang.ClassIterator.*;
 *

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

///

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

You could still use most of the features in **FastAPI** with the knowledge from the main [Tutorial - User Guide](../tutorial/index.md){.internal-link target=_blank}.

  /**
   * Indicates that a collection disallows certain elements (other than {@code null}, whose validity
   * as an element is indicated by the presence or absence of {@link #ALLOWS_NULL_VALUES}). From the
   * documentation for {@link Collection}:
   *
   * <blockquote>
   *
   * "Some collection implementations have restrictions on the elements that they may contain. For