* has zero slope).
 *
 * @author Pete Gillin
 * @since 20.0
 */
@J2ktIncompatible
@GwtIncompatible
public abstract class LinearTransformation {
  /**
   * Constructor for use by subclasses inside Guava.
   *
   * @deprecated Create instances by using the static factory methods of the class.
   */
  @Deprecated
  public LinearTransformation() {}

  /**

      }
      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.

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.

 * UnsupportedOperationException}.
 *
 * @author Charles Fry
 * @since 10.0
 */
@GwtCompatible
public abstract class AbstractCache<K, V> implements Cache<K, V> {

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

  /**
   * @since 11.0
   */
  @Override
  public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException {
    throw new UnsupportedOperationException();

abstract class TreeTraverser<T> {
  /** Constructor for use by subclasses. */
  public TreeTraverser() {}

  /**
   * Returns a tree traverser that uses the given function to navigate from a node to its children.
   * This is useful if the function instance already exists, or so that you can supply a lambda
   * expressions. If those circumstances don't apply, you probably don't need to use this; subclass

      return null;
    }
    return escapeUnsafe(c);
  }

  /**
   * Escapes a {@code char} value 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 characters.
   *
   * <p>Note that arrays returned by this method must not be modified once they have been returned.

@GwtCompatible
public abstract class AbstractIterator<T extends @Nullable Object> extends UnmodifiableIterator<T> {
  private State state = State.NOT_READY;

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

  private enum State {
    /** We have computed the next element and haven't returned it yet. */
    READY,

 * }
 *
 * @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

      @SuppressWarnings("unchecked")
      @Override
      <K extends K0, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
        // K must actually be K0, since enums are effectively final
        // (their subclasses are inaccessible)
        return (Map<K, Collection<V>>) new EnumMap<K0, Collection<V>>(keyClass);
      }
    };
  }

  private static final class ArrayListSupplier<V extends @Nullable Object>

      @SuppressWarnings("unchecked")
      @Override
      <K extends K0, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
        // K must actually be K0, since enums are effectively final
        // (their subclasses are inaccessible)
        return (Map<K, Collection<V>>) new EnumMap<K0, Collection<V>>(keyClass);
      }
    };
  }

  private static final class ArrayListSupplier<V extends @Nullable Object>