}

  private Absent() {}

  @Override
  public boolean isPresent() {
    return false;
  }

  @Override
  public T get() {
    throw new IllegalStateException("Optional.get() cannot be called on an absent value");
  }

  @Override
  public T or(T defaultValue) {
    return checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
  }

     */
    boolean available();

    /**
     * Cleans up resources and performs any necessary finalization tasks
     * before the object is destroyed. This method should be called to
     * ensure that all resources are properly released.
     */
    void destroy();

    /**
     * Initializes the CrawlerContainer by setting the system property

 * instance contains a list of listeners, each with an associated {@code Executor}, and guarantees
 * that every {@code Runnable} that is {@linkplain #add added} will be executed after {@link
 * #execute()} is called. Any {@code Runnable} added after the call to {@code execute} is still
 * guaranteed to execute. There is no guarantee, however, that listeners will be executed in the
 * order that they are added.
 *

  }

  /**
   * @return The event object that caused the subscriber to throw.
   */
  public Object getEvent() {
    return event;
  }

  /**
   * @return The object context that the subscriber was called on.
   */
  public Object getSubscriber() {
    return subscriber;
  }

  /**
   * @return The subscribed method that threw the exception.
   */
  public Method getSubscriberMethod() {

 *    other properties.
 *
 * Certificates are signed by other certificates and a sequence of them is called a certificate
 * chain. The chain terminates in a self-signed "root" certificate. Signing certificates in the
 * middle of the chain are called "intermediates". Organizations that offer certificate signing are
 * called certificate authorities (CAs).
 *

    * There is a **solution** to this, however.
* There's an **extension** to the **TLS** protocol (the one handling the encryption at the TCP level, before HTTP) called **<a href="https://en.wikipedia.org/wiki/Server_Name_Indication" class="external-link" target="_blank"><abbr title="Server Name Indication">SNI</abbr></a>**.

        when(src.openUnshared(eq(0), eq(SmbConstants.O_RDONLY), eq(SmbConstants.FILE_SHARE_READ), eq(SmbConstants.ATTR_NORMAL), eq(0)))
                .thenReturn(sfd);

        // openCopyTargetFile should be called by serverSideCopy, so dest.openUnshared must succeed
        SmbFileHandleImpl dfd = mock(SmbFileHandleImpl.class);
        when(dest.openUnshared(anyInt(), anyInt(), anyInt(), anyInt(), anyInt())).thenReturn(dfd);

## `PATH` Environment Variable { #path-environment-variable }

There is a **special** environment variable called **`PATH`** that is used by the operating systems (Linux, macOS, Windows) to find programs to run.

    CLOSED,

    /**
     * {@link ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)} has been
     * called. The step may not be further subsumed, nor may {@link #finishToFuture()} be called.
     */
    WILL_CREATE_VALUE_AND_CLOSER,
  }

        String::class.java,
        String::class.java,
      )
    } catch (_: NoSuchMethodException) {
      null
    }

  /** Android method to clean and sort certificates, called via reflection. */
  @Suppress("unused", "UNCHECKED_CAST")
  fun checkServerTrusted(
    chain: Array<out X509Certificate>,
    authType: String,
    host: String,
  ): List<Certificate> {