*   user task -- which means that we already got past this code (or else we exited early
       *   above))
       */
      // Unconditionally set; there is no risk of throwing away a queued task from another thread,
      // because in order for the current task to run on this executor the previous task must have

   *
   * If there are I/O problems during iteration, this iterator fails silently. For example, if the
   * hosting filesystem becomes unreachable, the iterator will omit elements rather than throwing
   * exceptions.
   *
   * **The caller must [close][Snapshot.close]** each snapshot returned by [Iterator.next]. Failing
   * to do so leaks open files!
   */
  @Synchronized
  @Throws(IOException::class)

   * {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the minus sign.
   *
   * <p>Unlike {@link Float#parseFloat(String)}, this method returns {@code null} instead of
   * throwing an exception if parsing fails. Valid inputs are exactly those accepted by {@link
   * Float#valueOf(String)}, except that leading and trailing whitespace is not permitted.
   *

     * <p>If the combiningCallable throws an {@code ExecutionException}, the cause of the thrown
     * {@code ExecutionException} will be extracted and used as the failure of the derived step.
     *
     * <p>If the combiningCallable throws any other exception, it will be used as the failure of the
     * derived step.
     *
     * <p>If an exception is thrown after the combiningCallable creates a {@code ClosingFuture},

  }

  public void testPuttingTheSameKeyTwiceThrowsOnBuild() {
    Builder<String, Integer> builder =
        new Builder<String, Integer>()
            .put("one", 1)
            .put("one", 1); // throwing on this line might be better but it's too late to change

    assertThrows(IllegalArgumentException.class, () -> builder.buildOrThrow());
  }

  public void testBuildKeepingLast_allowsOverwrite() {

   * {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the minus sign.
   *
   * <p>Unlike {@link Double#parseDouble(String)}, this method returns {@code null} instead of
   * throwing an exception if parsing fails. Valid inputs are exactly those accepted by {@link
   * Double#valueOf(String)}, except that leading and trailing whitespace is not permitted.
   *

    when the URL is malformed instead of returning null. Use this to avoid checking for null in
    situations where the input is known to be well-formed. We've also added `MediaType.get(String)`
    which is an exception-throwing alternative to `MediaType.parse(String)`.
 *  New: The `EventListener` API previewed in OkHttp 3.9 has graduated to a stable API. Use this
    interface to track metrics and monitor HTTP requests' size and duration.

        /*
         * We can't just return the iterator because an immediate call to its
         * remove() method would remove one of the skipped elements instead of
         * throwing an IllegalStateException.
         */
        return new Iterator<T>() {
          boolean atStart = true;

          @Override
          public boolean hasNext() {
            return iterator.hasNext();

  /**
   * Pre-defined {@link Policy} implementations.
   *
   * @since 13.0
   */
  public enum Policies implements Policy {
    /**
     * When potential deadlock is detected, this policy results in the throwing of the {@code
     * PotentialDeadlockException} indicating the potential deadlock, which includes stack traces
     * illustrating the cycle in lock acquisition order.
     */
    THROW {
      @Override

## Version 5.1.0

_2025-07-07_

 *  New: `Response.peekTrailers()`. When we changed `Response.trailers()` to block instead of
    throwing in 5.0.0, we inadvertently removed the ability for callers to peek the trailers
    (by catching the `IllegalStateException` if they weren't available). This new API restores that
    capability.