Minor Javadoc improvement.

PiperOrigin-RevId: 309329483
diff --git a/core/src/main/java/com/google/googlejavaformat/java/JavaInput.java b/core/src/main/java/com/google/googlejavaformat/java/JavaInput.java
index 17ae0fa..999c8fb 100644
--- a/core/src/main/java/com/google/googlejavaformat/java/JavaInput.java
+++ b/core/src/main/java/com/google/googlejavaformat/java/JavaInput.java
@@ -562,7 +562,7 @@
    * @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;