elements.add(null);
    collection = getSubjectGenerator().create(elements.toArray());
    assertEquals(
        "A Set's hashCode() should be the sum of those of its elements (with "
            + "a null element counting as having a hash of zero).",
        expectedHashCode,
        getSet().hashCode());
  }

  /**
   * Returns the {@link Method} instances for the test methods in this class which call {@code

 * @since 1.0
 */
@J2ktIncompatible
@GwtIncompatible
public final class CountingOutputStream extends FilterOutputStream {

  private long count;

  /**
   * Wraps another output stream, counting the number of bytes written.
   *
   * @param out the output stream to be wrapped
   */
  public CountingOutputStream(OutputStream out) {
    super(checkNotNull(out));
  }

  override fun writeTo(sink: BufferedSink) {
    writeOrCountBytes(sink, false)
  }

  /**
   * Either writes this request to [sink] or measures its content length. We have one method
   * do double-duty to make sure the counting and content are consistent, particularly when it comes
   * to awkward operations like measuring the encoded length of header strings, or the
   * length-in-digits of an encoded integer.
   */
  private fun writeOrCountBytes(

    elements.add(null);
    collection = getSubjectGenerator().create(elements.toArray());
    assertEquals(
        "A Set's hashCode() should be the sum of those of its elements (with "
            + "a null element counting as having a hash of zero).",
        expectedHashCode,
        getSet().hashCode());
  }

  /**
   * Returns the {@link Method} instances for the test methods in this class which call {@code