}

  public static class NoOpRunnable implements Runnable {
    @Override
    public void run() {}
  }

  public static class NoOpCallable implements Callable<Object> {
    @Override
    public Object call() {
      return Boolean.TRUE;
    }
  }

  public static final String TEST_STRING = "a test string";

  public static class StringTask implements Callable<String> {
    @Override

    // See https://github.com/google/guava/issues/1505
    assertThat(Finalizer.class.getDeclaredClasses()).isEmpty();
  }

  static class MyServerExampleWithFrq implements Closeable {
    private static final FinalizableReferenceQueue frq = new FinalizableReferenceQueue();

    private static final Set<Reference<?>> references = Sets.newConcurrentHashSet();

 * writeObject} methods.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
abstract class AbstractMapBasedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>
    implements Serializable {

  transient ObjectCountHashMap<E> backingMap;
  transient long size;

  AbstractMapBasedMultiset(int distinctElements) {
    backingMap = newBackingMap(distinctElements);
  }

  }

  private static final class ContainsMultiset implements Serializable {
    private final ConcurrentHashMultiset<?> multiset;

    ContainsMultiset(ConcurrentHashMultiset<?> multiset) {
      this.multiset = multiset;
    }
  }

  private static final class ContainsBothWithMultisetFirst implements Serializable {
    private final ConcurrentHashMultiset<?> a;

import org.codelibs.jcifs.smb.ntlmssp.Type3Message;

/**
 * JcifsEngine is a NTLM Engine implementation based on JCIFS.
 *
 * @author shinsuke
 *
 */
public class JcifsEngine implements NTLMEngine {

    /** Flags for Type 1 NTLM message. */
    protected static final int TYPE_1_FLAGS = NtlmFlags.NTLMSSP_NEGOTIATE_56 | NtlmFlags.NTLMSSP_NEGOTIATE_128

 * such as agent paths.
 *
 * @see org.apache.maven.api.services.DependencyResolverResult#getDispatchedPaths()
 *
 * @since 4.0.0
 */
@Experimental
public enum JavaPathType implements PathType {
    /**
     * The path identified by the Java {@code --class-path} option.
     * Used for compilation, execution and Javadoc among others.
     * The Java tools location is {@link StandardLocation#CLASS_PATH}.

    }

    interface ExpectedResult {}

    static class SelectedProjectsResult implements ExpectedResult {
        final List<String> projectNames;

        SelectedProjectsResult(List<String> projectSelectors) {
            this.projectNames = projectSelectors;
        }
    }

    static class ExceptionThrown implements ExpectedResult {
        final Class<? extends Throwable> expected;

httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

But possibly the most important part of the callback is making sure that your API user (the external developer) implements the *external API* correctly, according to the data that *your API* is going to send in the request body of the callback, etc.

  public Converter<String, String> converterTo(CaseFormat targetFormat) {
    return new StringConverter(this, targetFormat);
  }

  private static final class StringConverter extends Converter<String, String>
      implements Serializable {

    private final CaseFormat sourceFormat;
    private final CaseFormat targetFormat;

    StringConverter(CaseFormat sourceFormat, CaseFormat targetFormat) {

    return transformAsync(inputFuture, new ChainingFunction(), directExecutor());
  }

  @Override
  protected String getSuccessfulResult() {
    return RESULT_DATA;
  }

  private class ChainingFunction implements AsyncFunction<Integer, String> {
    @Override
    public ListenableFuture<String> apply(Integer input) throws Exception {
      switch (input) {
        case VALID_INPUT_DATA:
          outputFuture.set(RESULT_DATA);