internal fun FileSystem.deleteIfExists(path: Path) {
  try {
    delete(path)
  } catch (fnfe: FileNotFoundException) {
    return
  }
}

/** Tolerant delete, try to clear as many files as possible even after a failure. */
internal fun FileSystem.deleteContents(directory: Path) {
  var exception: IOException? = null
  val files =
    try {
      list(directory)

HTTPS
=====

OkHttp attempts to balance two competing concerns:

 * **Connectivity** to as many hosts as possible. That includes advanced hosts that run the latest versions of [boringssl](https://boringssl.googlesource.com/boringssl/) and less out of date hosts running older versions of [OpenSSL](https://www.openssl.org/).

      fun run() {
        val request = Request.Builder()
            .url("http://publicobject.com/secrets/hellosecret.txt")
            .build()
      }
    ```

    To avoid making many retries when authentication isn't working, you can return null to give up. For example, you may want to skip the retry when these exact credentials have already been attempted:

    ```kotlin

   * in the returned list.
   *
   * <p>The function is applied lazily, invoked when needed. This is necessary for the returned list
   * to be a view, but it means that the function will be applied many times for bulk operations
   * like {@link List#contains} and {@link List#hashCode}. For this to perform well, {@code
   * function} should be fast. To avoid lazy evaluation when the returned list doesn't need to be a

   * only the entries for {@code keys} will be returned from {@code getAll}.
   *
   * <p>This method should be overridden when bulk retrieval is significantly more efficient than
   * many individual lookups. Note that {@link LoadingCache#getAll} will defer to individual calls
   * to {@link LoadingCache#get} if this method is not overridden.
   *

     * best we can do (since logging may overflow the stack) is to let the error propagate. Because
     * it is an Error, it won't be caught and logged by AbstractFuture.executeListener. Instead, it
     * can propagate through many layers of AbstractTransformFuture up to the root call to set().
     *
     * https://github.com/google/guava/issues/2254
     *
     * Other kinds of Errors are possible:
     *

   *     minValue()}
   */
  public abstract @Nullable C previous(C value);

  /**
   * Returns a signed value indicating how many nested invocations of {@link #next} (if positive) or
   * {@link #previous} (if negative) are needed to reach {@code end} starting from {@code start}.

   * href="http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5Cp%7Bdigit%7D">Unicode</a>. If
   * you only care to match ASCII digits, you can use {@code inRange('0', '9')}.
   *
   * @deprecated Many digits are supplementary characters; see the class documentation.
   * @since 19.0 (since 1.0 as constant {@code DIGIT})
   */
  @Deprecated
  public static CharMatcher digit() {
    return Digit.INSTANCE;
  }

   * between elements will be made, but the order in which those pairs of elements are passed to the
   * consumer is <i>not</i> defined.
   *
   * <p>Note that many usages of this method can be replaced with simpler calls to {@link #zip}.
   * This method behaves equivalently to {@linkplain #zip zipping} the stream elements into

 *       actually do so, to avoid implying repeat-iterability.) {@code FluentIterable}, on the other
 *       hand, is multiple-use, and does implement {@link Iterable}.
 *   <li>Streams offer many features not found here, including {@code min/max}, {@code distinct},
 *       {@code reduce}, {@code sorted}, the very powerful {@code collect}, and built-in support for
 *       parallelizing stream operations.