It has the same fields as `HeroBase`, so it won't include `secret_name`.

Finally, the identity of our heroes is protected! 🥷

It also re-declares `id: int`. By doing this, we are making a **contract** with the API clients, so that they can always expect the `id` to be there and to be an `int` (it will never be `None`).

/// tip

import org.codelibs.fess.crawler.entity.ResponseData;
import org.codelibs.fess.crawler.processor.ResponseProcessor;
import org.dbflute.utflute.core.PlainTestCase;

/**
 * Test class for Rule interface.
 * Tests the contract and behavior of Rule implementations.
 */
public class RuleTest extends PlainTestCase {

    /**
     * Test implementation of Rule interface for testing purposes
     */

import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests representing the contract of {@link Map}. Concrete subclasses of this base class test
 * conformance of concrete {@link Map} subclasses to that contract.
 *
 * @param <K> the type of keys used by the maps under test
 * @param <V> the type of mapped values used the maps under test
 * @author George van den Driessche

      return Iterators.unmodifiableIterator(iterable.iterator());
    }

    @Override
    public String toString() {
      return iterable.toString();
    }
    // no equals and hashCode; it would break the contract!
  }

  /** Returns the number of elements in {@code iterable}. */
  public static int size(Iterable<?> iterable) {
    return (iterable instanceof Collection)
        ? ((Collection<?>) iterable).size()

import org.codelibs.fess.crawler.entity.ResultData;
import org.codelibs.fess.crawler.exception.CrawlerSystemException;
import org.dbflute.utflute.core.PlainTestCase;

/**
 * Test class for Transformer interface.
 * Tests the contract and behavior of Transformer implementations.
 */
public class TransformerTest extends PlainTestCase {

    /**
     * Basic test implementation of Transformer
     */

 * which approach to use, <b>don't worry</b> too much about it; just pick something that seems
 * reasonable and it will be fine.
 *
 * <ul>
 *   <li>If checking whether the <i>caller</i> has violated your method or constructor's contract
 *       (such as by passing an invalid argument), use the utilities of the {@link Preconditions}
 *       class instead.
 *   <li>If checking an <i>impossible</i> condition (which <i>cannot</i> happen unless your own

          // Checking subtype between declared and actual type bounds
          // adds recursive isSubtypeOf() call and feels complicated.
          // There is no contract one way or another as long as isSubtypeOf() works as expected.
          combined.addAll(asList(typeParam.getBounds()));
          if (combined.size() > 1) { // Object is implicit and only useful if it's the only bound.

        // This cast is not itself safe, but the following statement
        // will fail if the runtime type of items[i] is not assignable
        // to the runtime type of a[k++], which is all that the method
        // contract requires (see @throws ArrayStoreException above).
        @SuppressWarnings("unchecked")
        T t = (T) items[i];
        a[k++] = t;
        i = inc(i);
      }
      if (a.length > count) a[count] = null;

        return method.invoke(obj, args);
    }

    /**
     * Tests for the TreeConnectResponse interface using a mock implementation
     */
    @Nested
    @DisplayName("Interface Contract Tests")
    class InterfaceTests {

        private TreeConnectResponse mockResponse;

        @BeforeEach
        void setUp() {
            mockResponse = mock(TreeConnectResponse.class);
        }

      return (Spliterator<T>) iterable.spliterator();
    }

    @Override
    public String toString() {
      return iterable.toString();
    }
    // no equals and hashCode; it would break the contract!
  }

  /** Returns the number of elements in {@code iterable}. */
  public static int size(Iterable<?> iterable) {
    return (iterable instanceof Collection)
        ? ((Collection<?>) iterable).size()