* @return {@code string} if it is not null; {@code ""} otherwise
   */
  static String nullToEmpty(@Nullable String string) {
    return (string == null) ? "" : string;
  }

  /**
   * Returns the string if it is not empty, or a null string otherwise.
   *
   * @param string the string to test and possibly return
   * @return {@code string} if it is not empty; {@code null} otherwise
   */

 * Outer class that exists solely to let us write {@code Partially.GwtIncompatible} instead of plain
 * {@code GwtIncompatible}. This is more accurate for {@link Futures#catching}, which is available
 * under GWT but with a slightly different signature.
 *
 * <p>We can't use {@code PartiallyGwtIncompatible} because then the GWT compiler wouldn't recognize
 * it as a {@code GwtIncompatible} annotation. And for {@code Futures.catching}, we need the GWT

        sink.writeUtf8(requestMethod).writeByte('\n'.code)
        sink.writeDecimalLong(varyHeaders.size.toLong()).writeByte('\n'.code)
        for (i in 0 until varyHeaders.size) {
          sink
            .writeUtf8(varyHeaders.name(i))
            .writeUtf8(": ")
            .writeUtf8(varyHeaders.value(i))
            .writeByte('\n'.code)
        }

      return this;
    }

    /**
     * Adds each element of {@code elements} to the {@code ImmutableSet}, ignoring duplicate
     * elements (only the first duplicate element is added).
     *
     * @param elements the elements to add
     * @return this {@code Builder} object
     * @throws NullPointerException if {@code elements} is null or contains a null element
     */
    @Override

    this(chunkSize, chunkSize);
  }

  /**
   * Constructor for use by subclasses. This hasher instance will process chunks of the specified
   * size, using an internal buffer of {@code bufferSize} size, which must be a multiple of {@code
   * chunkSize}.
   *
   * @param chunkSize the number of bytes available per {@link #process(ByteBuffer)} invocation;
   *     must be at least 4

///

## 프로젝트 생성

먼저, 프로젝트를 위한 디렉터리를 하나 생성합니다.

보통 사용자 홈 디렉터리 안에 `code`라는 디렉터리를 만들고, 그 안에 프로젝트마다 하나씩 디렉터리를 만들어 관리합니다.

<div class="termy">

```console
// 홈 디렉터리로 이동
$ cd
// 모든 코드 프로젝트를 위한 디렉터리 생성
$ mkdir code
// code 디렉터리로 이동
$ cd code
// 이번 프로젝트를 위한 디렉터리 생성
$ mkdir awesome-project
// 해당 프로젝트 디렉터리로 이동
$ cd awesome-project
```

</div>

 * accounts. SIDs are commonly represented using a textual format such as
 * {@code S-1-5-21-1496946806-2192648263-3843101252-1029} but they may
 * also be resolved to yield the name of the associated Windows account
 * such as {@code Administrators} or {@code MYDOM\alice}.
 * <p>
 * Consider the following output of {@code examples/SidLookup.java}:
 * <pre>
 *        toString: S-1-5-21-4133388617-793952518-2001621813-512

The zoneinfo.zip archive contains time zone files compiled using
the code and data maintained as part of the IANA Time Zone Database.
The IANA asserts that the database is in the public domain.

For more information, see
https://www.iana.org/time-zones
ftp://ftp.iana.org/tz/code/tz-link.html
https://datatracker.ietf.org/doc/html/rfc6557

   *
   * Note that transport-layer success (receiving a HTTP response code, headers and body) does not
   * necessarily indicate application-layer success: `response` may still indicate an unhappy HTTP
   * response code like 404 or 500.
   *
   * @throws IOException if the request could not be executed due to cancellation, a connectivity

 *
 * @author Ben Yu
 */
@GwtIncompatible
@J2ktIncompatible
@NullMarked
abstract class DummyProxy {

  /**
   * Returns a new proxy for {@code interfaceType}. Proxies of the same interface are equal to each
   * other if the {@link DummyProxy} instance that created the proxies are equal.
   */
  final <T> T newProxy(TypeToken<T> interfaceType) {