StringBuilder builder = new StringBuilder();
    Writer writer = new AppendableWriter(builder);

    writer.append("Hello,");
    writer.append(' ');
    writer.append("The World Wide Web", 4, 9);
    writer.append("!");

    assertEquals("Hello, World!", builder.toString());
  }

  public void testCloseFlush() throws IOException {
    SpyAppendable spy = new SpyAppendable();

   *
   * @param expected expected value of {@link #container}
   */
  /*
   * TODO: improve this and other implementations and move out of this framework
   * for wider use
   *
   * TODO: could we incorporate the overriding logic from AbstractListTester, by
   * examining whether the features include KNOWN_ORDER?
   */
  protected void expectContents(Collection<E> expected) {

   *
   * @param expected expected value of {@link #container}
   */
  /*
   * TODO: improve this and other implementations and move out of this framework
   * for wider use
   *
   * TODO: could we incorporate the overriding logic from AbstractListTester, by
   * examining whether the features include KNOWN_ORDER?
   */
  protected void expectContents(Collection<E> expected) {

import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Stream;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Supplies an arbitrary "default" instance for a wide range of types, often useful in testing
 * utilities.
 *
 * <p>Covers arrays, enums and common types defined in {@code java.lang}, {@code java.lang.reflect},

import java.util.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Supplies an arbitrary "default" instance for a wide range of types, often useful in testing
 * utilities.
 *
 * <p>Covers arrays, enums and common types defined in {@code java.lang}, {@code java.lang.reflect},

     * @param closingExecutor the object will be closed on this executor
     * @return the first argument
     */
    @CanIgnoreReturnValue
    @ParametricNullness
    // TODO(b/163345357): Widen bound to AutoCloseable once we require API Level 19.
    public <C extends @Nullable Object & @Nullable Closeable> C eventuallyClose(
        @ParametricNullness C closeable, Executor closingExecutor) {

    StringBuilder builder = new StringBuilder();
    Writer writer = new AppendableWriter(builder);

    writer.append("Hello,");
    writer.append(' ');
    writer.append("The World Wide Web", 4, 9);
    writer.append("!");

    assertEquals("Hello, World!", builder.toString());
  }

  public void testCloseFlush() throws IOException {
    SpyAppendable spy = new SpyAppendable();