Minor Javadoc improvement.

PiperOrigin-RevId: 309329483

Author: google-java-format Team

core/src/main/java/com/google/googlejavaformat/java/JavaInput.java

@@ -562,7 +562,7 @@ private static boolean isParamComment(Tok tok) {
    * @param offset the {@code 0}-based offset in characters
    * @param length the length in characters
    * @return the {@code 0}-based {@link Range} of tokens
-   * @throws FormatterException
+   * @throws FormatterException if offset + length is outside the file
    */
   Range<Integer> characterRangeToTokenRange(int offset, int length) throws FormatterException {
     int requiredLength = offset + length;