* situations, you may wish to override {@link SortedMultiset#elementSet} to forward to this
   * implementation or a subclass thereof.
   */
  protected class StandardElementSet extends SortedMultisets.ElementSet<E> {
    /** Constructor for use by subclasses. */
    public StandardElementSet() {
      super(ForwardingSortedMultiset.this);
    }
  }

  @Override

import java.util.concurrent.Callable;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A listening executor service which forwards all its method calls to another listening executor
 * service. Subclasses should override one or more methods to modify the behavior of the backing
 * executor service as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

   * ForwardingSortedMap}. In many cases, you may wish to override {@link
   * ForwardingSortedMap#keySet} to forward to this implementation or a subclass thereof.
   *
   * @since 15.0
   */
  protected class StandardKeySet extends Maps.SortedKeySet<K, V> {
    /** Constructor for use by subclasses. */
    public StandardKeySet() {
      super(ForwardingSortedMap.this);
    }
  }

    }
  }

  /** Constructor for use by subclasses. */
  protected AbstractIdleService() {}

  /** Start the service. */
  protected abstract void startUp() throws Exception;

  /** Stop the service. */
  protected abstract void shutDown() throws Exception;

  /**
   * Returns the {@link Executor} that will be used to run this service. Subclasses may override

   * situations, you may wish to override {@link SortedMultiset#elementSet} to forward to this
   * implementation or a subclass thereof.
   *
   * @since 15.0
   */
  protected class StandardElementSet extends SortedMultisets.NavigableElementSet<E> {
    /** Constructor for use by subclasses. */
    public StandardElementSet() {
      super(ForwardingSortedMultiset.this);
    }
  }

  @Override

    Actually, `Query`, `Path` and others you'll see next create objects of subclasses of a common `Param` class, which is itself a subclass of Pydantic's `FieldInfo` class.

    And Pydantic's `Field` returns an instance of `FieldInfo` as well.

    `Body` also returns objects of a subclass of `FieldInfo` directly. And there are others you will see later that are subclasses of the `Body` class.

import java.util.concurrent.Callable;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A listening executor service which forwards all its method calls to another listening executor
 * service. Subclasses should override one or more methods to modify the behavior of the backing
 * executor service as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

    }
  }

  /** Constructor for use by subclasses. */
  protected AbstractIdleService() {}

  /** Start the service. */
  protected abstract void startUp() throws Exception;

  /** Stop the service. */
  protected abstract void shutDown() throws Exception;

  /**
   * Returns the {@link Executor} that will be used to run this service. Subclasses may override

   * </ul>
   *
   * <p>Subclasses can override this method to provide custom equality.
   */
  @Override
  public boolean equals(@CheckForNull Object obj) {
    return super.equals(obj);
  }

  /**
   * By default delegates to {@link Object#hashCode}. The dynamic proxies' {@code hashCode()} will
   * delegate to this method. Subclasses can override this method to provide custom equality.
   */

   * ForwardingSortedMap}. In many cases, you may wish to override {@link
   * ForwardingSortedMap#keySet} to forward to this implementation or a subclass thereof.
   *
   * @since 15.0
   */
  protected class StandardKeySet extends Maps.SortedKeySet<K, V> {
    /** Constructor for use by subclasses. */
    public StandardKeySet() {
      super(ForwardingSortedMap.this);
    }
  }