// Then
        assertNotSame(instance1, instance2);
        assertEquals(instance1.getCommand(), instance2.getCommand());
        assertNotEquals(instance1.toString(), instance2.toString()); // Different object references in toString
    }

    /**
     * Test thread safety of read/write operations
     */
    @Test
    @DisplayName("Test thread safety of operations")

        } catch (final Exception e) {
            logger.warn("Failed to get active instances.", e);
        }
        return instances;
    }

    /**
     * Checks whether the specified instance is currently active.
     *
     * @param targetInstanceId the instance ID to check.
     * @return {@code true} if the instance is active.
     */
    public boolean isInstanceActive(final String targetInstanceId) {

        final List<InstanceInfo> instances = helper.getActiveInstances();

        assertEquals(2, instances.size());
        assertEquals("node1@host1", instances.get(0).instanceId);
        assertEquals("host1", instances.get(0).hostname);
        assertEquals("node1", instances.get(0).name);
        assertEquals(1000L, instances.get(0).lastSeen);
        assertEquals("node2@host2", instances.get(1).instanceId);

  <version>0.0.0.0</version>
</parent>
    ]]></configuration>
    <description> This is the MavenProject instance for the parent of the current POM.
    </description>
  </expression>
  <expression>
    <syntax>project.file</syntax>
    <description> This is the File instance that refers to the location of the current POM on
      disk.
    </description>
  </expression>
  <expression>

   *       is used to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.
   *   <li>For the constructor or static factory method used to construct instances, it's checked
   *       that when equal parameters are passed, the result instance should also be equal; and vice
   *       versa.

   *       is used to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.
   *   <li>For the constructor or static factory method used to construct instances, it's checked
   *       that when equal parameters are passed, the result instance should also be equal; and vice
   *       versa.

   *       to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.
   *   <li>For the constructor or static factory method used to construct instances, it's checked
   *       that when equal parameters are passed, the result instance should also be equal; and vice
   *       versa.

    }

    /**
     * Creates a new RequestDataContext for building RequestData instances.
     *
     * @return a new RequestDataContext instance
     */
    public static RequestDataContext newRequestData() {
        return new RequestDataContext();
    }

    /**
     * Context class for building RequestData instances using a fluent API.
     */
    public static class RequestDataContext {

    }
  }

  /** Returns a fresh {@link InternerBuilder} instance. */
  public static InternerBuilder newBuilder() {
    return new InternerBuilder();
  }

  /**
   * Returns a new thread-safe interner which retains a strong reference to each instance it has
   * interned, thus preventing these instances from being garbage-collected. If this retention is

        // Test that constructor creates a non-null instance
        assertNotNull(crawlerEngineClient);
    }

    // Test inheritance
    @Test
    public void test_inheritance() {
        // Test that CrawlerEngineClient is properly inherited
        assertTrue(crawlerEngineClient instanceof org.codelibs.fess.crawler.client.FesenClient);
    }

    // Test multiple instances
    @Test
    public void test_multipleInstances() {