*     in this instance of the Java virtual machine
   */
  public Optional<Charset> charset() {
    // racy single-check idiom, this is safe because Optional is immutable.
    Optional<Charset> local = parsedCharset;
    if (local == null) {
      String value = null;
      local = Optional.absent();

        service.startAsync();
      } catch (IllegalStateException e) {
        // This can happen if the service has already been started or stopped (e.g. by another
        // service or listener). Our contract says it is safe to call this method if
        // all services were NEW when it was called, and this has already been verified above, so we
        // don't propagate the exception.

 * the context of {@code class MyStringList implements List<String>}). In such case, prefer to use
 * {@link TypeToken#resolveType} since it's simpler and more type safe. This class should only be
 * used when the type mapping isn't implied by the static type hierarchy, but provided through other
 * means such as an annotation or external configuration file.
 *
 * @author Ben Yu
 * @since 15.0

There's also the chance that for some reason you have a **spike** of usage of your API. Maybe it went viral, or maybe some other services or bots start using it. And you might want to have extra resources to be safe in those cases.

            + "^\\s*data:|" //
            + "^\\s*android-app:|" //
            + "^\\s*ios-app:|" //
            + "^\\s*callto:", Pattern.CASE_INSENSITIVE);

    /** Thread-local XPathAPI instance for thread-safe XPath operations. */
    private final ThreadLocal<XPathAPI> xpathAPI = new ThreadLocal<>();

    @Override
    public ResultData transform(final ResponseData responseData) {

   * B>`, convertAll could accept and return iterables with nullable element types. In both cases,
   * we've chosen to instead use a signature that benefits existing users -- and is still safe.
   *
   * For convertAll, I haven't looked as closely at *how* much existing users benefit, so we should
   * keep an eye out for problems that new users encounter. Note also that convertAll could support

type Writer struct {
	w    io.Writer
	pad  int64      // Amount of padding to write after current file entry
	curr fileWriter // Writer for current file entry
	hdr  Header     // Shallow copy of Header that is safe for mutations
	blk  block      // Buffer to use as temporary local storage

	// err is a persistent error.
	// It is only the responsibility of every exported method of Writer to
	// ensure that this error is sticky.

   * in the manner of {@link Number#intValue}.
   *
   * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}.
   * Calling this method is as thread-safe as calling that method.
   *
   * @param collection a collection of {@code Number} instances
   * @return an array containing the same values as {@code collection}, in the same order, converted
   *     to primitives

    streamId: Int,
    outFinished: Boolean,
    alternating: List<Header>,
  ) {
    writer.headers(outFinished, streamId, alternating)
  }

  /**
   * Callers of this method are not thread safe, and sometimes on application threads. Most often,
   * this method will be called to send a buffer worth of data to the peer.
   *
   * Writes are subject to the write window of the stream and the connection. Until there is a

  // The organization of this test class is unusual, as it's not done by
  // method, but by overall "scenario". Also, the variety of actual tests we
  // do borders on absurd overkill. Better safe than sorry, though?

  @GwtIncompatible // java.util.BitSet
  public void testSetBits() {
    doTestSetBits(CharMatcher.any());
    doTestSetBits(CharMatcher.none());
    doTestSetBits(is('a'));