doTestCollapseWithNoChange("");
    doTestCollapseWithNoChange("x");
    doTestCollapseWithNoChange("xx");
  }

  private void doTestCollapse(String in, String out) {
    // Try a few different matchers which all match '-' and not 'x'
    // Try replacement chars that both do and do not change the value.
    for (char replacement : new char[] {'_', '-'}) {
      String expected = out.replace('_', replacement);

    doTestCollapseWithNoChange("");
    doTestCollapseWithNoChange("x");
    doTestCollapseWithNoChange("xx");
  }

  private void doTestCollapse(String in, String out) {
    // Try a few different matchers which all match '-' and not 'x'
    // Try replacement chars that both do and do not change the value.
    for (char replacement : new char[] {'_', '-'}) {
      String expected = out.replace('_', replacement);

 * FutureTask}, {@code ListenableFutureTask} does not provide an overrideable {@link
 * FutureTask#done() done()} method. For similar functionality, call {@link #addListener}.
 *
 * <p>Few users should use this class. It is intended primarily for those who are implementing an
 * {@code ExecutorService}. Most users should call {@link ListeningExecutorService#submit(Callable)

    // It turns out that creating a new String is usually as fast, or faster
    // than wrapping cbuf in a light-weight CharSequence.
    target.append(new String(cbuf, off, len));
  }

  /*
   * Override a few functions for performance reasons to avoid creating unnecessary strings.
   */

  @Override
  public void write(int c) throws IOException {
    checkNotClosed();
    target.append((char) c);
  }

  @Override

 * FutureTask}, {@code ListenableFutureTask} does not provide an overrideable {@link
 * FutureTask#done() done()} method. For similar functionality, call {@link #addListener}.
 *
 * <p>Few users should use this class. It is intended primarily for those who are implementing an
 * {@code ExecutorService}. Most users should call {@link ListeningExecutorService#submit(Callable)

How to contribute
=================

Thank you so much for wanting to contribute to Guava! Here are a few important
things you should know about contributing:

1.  API changes require discussion, use cases, etc. Code comes later.
2.  Pull requests are great for small fixes for bugs, documentation, etc.
3.  Pull requests are not merged directly into the master branch.
4.  Code contributions require signing a Google CLA.

API changes
-----------

 *
 * <p>The classes in this package include:
 *
 * <h2>Immutable collections</h2>
 *
 * These are collections whose contents will never change. They also offer a few additional
 * guarantees (see {@link ImmutableCollection} for details). Implementations are available for both
 * the JDK collection types and the Guava collection types (listed below).
 *
 * <h2>Collection types</h2>
 *

 *
 * <p>The classes in this package include:
 *
 * <h2>Immutable collections</h2>
 *
 * These are collections whose contents will never change. They also offer a few additional
 * guarantees (see {@link ImmutableCollection} for details). Implementations are available for both
 * the JDK collection types and the Guava collection types (listed below).
 *
 * <h2>Collection types</h2>
 *

 *
 * <p>The simplest use case is:
 *
 * <pre>
 * new EqualsTester().addEqualityGroup(foo).testEquals();
 * </pre>
 *
 * <p>This tests {@code foo.equals(foo)}, {@code foo.equals(null)}, and a few other operations.
 *
 * <p>For more extensive testing, add multiple equality groups. Each group should contain objects
 * that are equal to each other but unequal to the objects in any other group. For example:
 *
 * <pre>

 *
 * <p>The simplest use case is:
 *
 * <pre>
 * new EqualsTester().addEqualityGroup(foo).testEquals();
 * </pre>
 *
 * <p>This tests {@code foo.equals(foo)}, {@code foo.equals(null)}, and a few other operations.
 *
 * <p>For more extensive testing, add multiple equality groups. Each group should contain objects
 * that are equal to each other but unequal to the objects in any other group. For example:
 *
 * <pre>