copyTo(prefix, 0, byteCount)
    for (i in 0 until 16) {
      if (prefix.exhausted()) {
        break
      }
      val codePoint = prefix.readUtf8CodePoint()
      if (Character.isISOControl(codePoint) && !Character.isWhitespace(codePoint)) {
        return false
      }
    }
    return true
  } catch (_: EOFException) {
    return false // Truncated UTF-8 sequence.
  }

  // of the open-source view of the tests.

  @J2ktIncompatible
  @GwtIncompatible // Character.isISOControl
  public void testJavaIsoControl() {
    for (int c = 0; c <= Character.MAX_VALUE; c++) {
      assertEquals(
          "" + c, Character.isISOControl(c), CharMatcher.javaIsoControl().matches((char) c));
    }
  }

  // of the open-source view of the tests.

  @J2ktIncompatible
  @GwtIncompatible // Character.isISOControl
  public void testJavaIsoControl() {
    for (int c = 0; c <= Character.MAX_VALUE; c++) {
      assertEquals(
          "" + c, Character.isISOControl(c), CharMatcher.javaIsoControl().matches((char) c));
    }
  }

            int pos = escaped.indexOf(escapedHighlightPre);
            while (pos >= 0) {
                final int c = escaped.codePointAt(pos);
                if (Character.isISOControl(c) || highlightTerminalCharSet.contains(c)) {
                    break;
                }
                pos--;
            }

            value = escaped.substring(pos + 1);
        } else {

  @Deprecated
  public static CharMatcher javaLowerCase() {
    return JavaLowerCase.INSTANCE;
  }

  /**
   * Determines whether a character is an ISO control character as specified by {@link
   * Character#isISOControl(char)}.
   *
   * <p>All ISO control codes are on the BMP and thus supported by this API.
   *
   * @since 19.0 (since 1.0 as constant {@code JAVA_ISO_CONTROL})
   */