* class. For example, testing that {@code nodes()} method returns the set of the nodes in the
 * graph. The following test cases are left for the subclasses to handle:
 *
 * <ul>
 *   <li>Test cases related to whether the graph is directed, undirected, mutable, or immutable.
 *   <li>Test cases related to the specific implementation of the {@link Network} interface.
 * </ul>

     * Returns a builder that builds the unserialized type. Subclasses should override this method.
     */
    Builder<K, V> makeBuilder(int size) {
      return new Builder<>(size);
    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
  }

  /**
   * Returns a serializable form of this object. Non-public subclasses should not override this

     * Returns a builder that builds the unserialized type. Subclasses should override this method.
     */
    Builder<K, V> makeBuilder(int size) {
      return new Builder<>(size);
    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
  }

  /**
   * Returns a serializable form of this object. Non-public subclasses should not override this

 * }
 *
 * @author Charles Fry
 * @since 10.0
 */
@GwtCompatible
public abstract class CacheLoader<K, V> {
  /** Constructor for use by subclasses. */
  protected CacheLoader() {}

  /**
   * Computes or retrieves the value corresponding to {@code key}.
   *
   * @param key the non-null key whose value should be loaded

      } catch (ClassCastException wastNotComparableToOurType) {
        return false;
      }
    }
    return false;
  }

  // Prevent "missing hashCode" warning by explicitly forcing subclasses implement it
  @Override
  public abstract int hashCode();

  /*
   * The implementation neither produces nor consumes any non-null instance of type C, so
   * casting the type parameter is safe.
   */

/**
 * Helper classes for various benchmarks.
 *
 * @author Christopher Swenson
 */
@NullUnmarked
final class BenchmarkHelpers {
  /** So far, this is the best way to test various implementations of {@link Set} subclasses. */
  public interface CollectionsImplEnum {
    <E extends Comparable<E>> Collection<E> create(Collection<E> contents);

    String name();
  }

  public interface MapsImplEnum {

 * </ul>
 *
 * @since 14.0
 * @author Colin Decker
 */
@J2ktIncompatible
@GwtIncompatible
public abstract class ByteSource {

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

  /**
   * Returns a {@link CharSource} view of this byte source that decodes bytes read from this source
   * as characters using the given {@link Charset}.
   *

And these models are all sharing a lot of the data and duplicating attribute names and types.

We could do better.

We can declare a `UserBase` model that serves as a base for our other models. And then we can make subclasses of that model that inherit its attributes (type declarations, validation, etc).

All the data conversion, validation, documentation, etc. will still work as normally.

      }
      index++;
    }
    return index;
  }

  /**
   * Escapes a code point that has no direct explicit value in the replacement array and lies
   * outside the stated safe range. Subclasses should override this method to provide generalized
   * escaping for code points if required.
   *
   * <p>Note that arrays returned by this method must not be modified once they have been returned.

   *
   * @author Luke Sandberg
   * @since 15.0 (present as an interface in 13.0)
   */
  abstract class Listener {
    /** Constructor for use by subclasses. */
    public Listener() {}

    /**
     * Called when the service transitions from {@linkplain State#NEW NEW} to {@linkplain