assertTrue(transformer.isValidUrl("http://www.example.com"));
        assertTrue(transformer.isValidUrl("http://www.example.com/aaa"));
        assertTrue(transformer.isValidUrl("https://www.example.com"));
        assertTrue(transformer.isValidUrl("://www.example.com"));
        assertTrue(transformer.isValidUrl("//www.example.com"));

        assertFalse(transformer.isValidUrl(null));

<!DOCTYPE components PUBLIC "-//DBFLUTE//DTD LastaDi 1.0//EN"
	"http://dbflute.org/meta/lastadi10.dtd">
<components namespace="fessCrawler">
	<include path="crawler/container.xml" />
	<include path="crawler/transformer.xml" />

	<component name="ruleManager" class="org.codelibs.fess.crawler.rule.impl.RuleManagerImpl" instance="prototype">
		<postConstruct name="addRule">
			<arg>sitemapsRule</arg>
		</postConstruct>

    // objectKeyed = transformEntries(map6, transformer);
    // objectKeyed = transformEntries(map8, transformer);
    // objectKeyed = transformEntries(map9, transformer);
    // numberKeyed = transformEntries(map8, transformer);
    // numberKeyed = transformEntries(map9, transformer);

    // Can't loosen the value type:
    // Map<Number, Number> looseValued1 = transformEntries(map5, transformer);

     *       v2)} implies that {@code Objects.equals(transformer.transform(k1, v1),
     *       transformer.transform(k2, v2))}.
     * </ul>
     *
     * @throws NullPointerException if the key or value is null and this transformer does not accept
     *     null arguments
     */
    @ParametricNullness

     *       v2)} implies that {@code Objects.equals(transformer.transform(k1, v1),
     *       transformer.transform(k2, v2))}.
     * </ul>
     *
     * @throws NullPointerException if the key or value is null and this transformer does not accept
     *     null arguments
     */
    @ParametricNullness

    final EntryTransformer<? super K, ? super V1, V2> transformer;

    TransformedEntriesMultimap(
        Multimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
      this.fromMultimap = checkNotNull(fromMultimap);
      this.transformer = checkNotNull(transformer);
    }

    Collection<V2> transform(@ParametricNullness K key, Collection<V1> values) {

    final EntryTransformer<? super K, ? super V1, V2> transformer;

    TransformedEntriesMultimap(
        Multimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
      this.fromMultimap = checkNotNull(fromMultimap);
      this.transformer = checkNotNull(transformer);
    }

    Collection<V2> transform(@ParametricNullness K key, Collection<V1> values) {

```

### Key Design Patterns

- **Factory**: `CrawlerClientFactory`, `ExtractorFactory` - protocol/format-specific component selection
- **Strategy**: `CrawlerClient`, `Extractor`, `Transformer` - pluggable implementations
- **Builder**: `RequestDataBuilder`, `ExtractorBuilder` - fluent construction
- **Template Method**: `AbstractCrawlerClient`, `AbstractExtractor` - common logic with overrides

        output.cancel(false);
        throw new SomeUncheckedException();
      }
    }
    Transformer transformer = new Transformer();
    SettableFuture<Object> input = SettableFuture.create();

    ListenableFuture<Object> output = transform(input, transformer, directExecutor());
    transformer.output = output;

    input.set("foo");
    assertTrue(output.isCancelled());
  }

        output.cancel(false);
        throw new SomeUncheckedException();
      }
    }
    Transformer transformer = new Transformer();
    SettableFuture<Object> input = SettableFuture.create();

    ListenableFuture<Object> output = transform(input, transformer, directExecutor());
    transformer.output = output;

    input.set("foo");
    assertTrue(output.isCancelled());
  }