}

    private static boolean isEmpty(Object value) {
      // Put types estimated to be the most frequent first.
      if (value instanceof CharSequence) {
        return ((CharSequence) value).length() == 0;
      } else if (value instanceof Collection) {
        return ((Collection<?>) value).isEmpty();
      } else if (value instanceof Map) {

    return this;
  }

  /*
   * Note: hashString(CharSequence, Charset) is intentionally not overridden.
   *
   * While intuitively, using CharsetEncoder to encode the CharSequence directly to the buffer (or
   * even to an intermediate buffer) should be considerably more efficient than potentially
   * copying the CharSequence to a String and then calling getBytes(Charset) on that String, in

  }

  public void testGetGenericSuperclass_wildcard_boundIsInterface() {
    assertNull(TypeToken.of(Types.subtypeOf(CharSequence.class)).getGenericSuperclass());
    assertEquals(
        new TypeToken<CharSequence[]>() {},
        TypeToken.of(Types.subtypeOf(CharSequence[].class)).getGenericSuperclass());
  }

  public <T> void testGetGenericInterfaces_typeVariable_unbounded() {

 * javadoc for details.
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class CommonPattern {
  public abstract CommonMatcher matcher(CharSequence t);

  public abstract String pattern();

  public abstract int flags();

  // Re-declare this as abstract to force subclasses to override.
  @Override
  public abstract String toString();

 * javadoc for details.
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class CommonPattern {
  public abstract CommonMatcher matcher(CharSequence t);

  public abstract String pattern();

  public abstract int flags();

  // Re-declare this as abstract to force subclasses to override.
  @Override
  public abstract String toString();

        return str == null ? defaultStr : str;
    }

    /**
     * <p>Checks if the CharSequence contains only ASCII printable characters.</p>
     *
     * <p>{@code null} will return {@code false}.
     * An empty CharSequence (length()=0) will return {@code true}.</p>
     *
     * <pre>
     * StringUtils.isAsciiPrintable(null)     = false

            }
        }
        return input;
    }

    public boolean hasUAMathcer() {
        return StringUtil.isNotBlank(getUserAgent());
    }

    public Matcher getUAMatcher(final CharSequence input) {
        if (!hasUAMathcer()) {
            return null;
        }

        if (userAgentPattern == null) {
            userAgentPattern = Pattern.compile(getUserAgent());
        }

  private final Pattern pattern;

  JdkPattern(Pattern pattern) {
    this.pattern = Preconditions.checkNotNull(pattern);
  }

  @Override
  public CommonMatcher matcher(CharSequence t) {
    return new JdkMatcher(pattern.matcher(t));
  }

  @Override
  public String pattern() {
    return pattern.pattern();
  }

  @Override
  public int flags() {
    return pattern.flags();

   * time and space.
   *
   * @throws IllegalArgumentException if {@code sequence} contains ill-formed UTF-16 (unpaired
   *     surrogates)
   */
  public static int encodedLength(CharSequence sequence) {
    // Warning to maintainers: this implementation is highly optimized.
    int utf16Length = sequence.length();
    int utf8Length = utf16Length;
    int i = 0;

    // This loop optimizes for pure ASCII.

       * built-in nullness feature?
       */
      "ExtendsObject",
    })
    <T extends Object> void withObjectBound(List<T> list) {}

    @SuppressWarnings("unused")
    <T extends Number & CharSequence> void withUpperBound(List<T> list) {}

    static TypeVariable<?> getTypeVariable(String methodName) throws Exception {
      ParameterizedType parameterType =
          (ParameterizedType)