Add comment to indicate necessity of alignment with upstream implementation. (#215, f64cbde)

Author: blackwinter

metafix/src/main/java/org/metafacture/metafix/Value.java

@@ -462,6 +462,7 @@ public void remove(final int index) {
      */
     public static class Hash extends AbstractValueType {
 
+        // NOTE: Keep in sync with `WildcardTrie`/`SimpleRegexTrie` implementation in metafacture-core.
         private static final Matcher PATTERN_MATCHER = Pattern.compile("[*?|]|\\[[^\\]]").matcher("");
 
         private static final Map<String, Map<String, Boolean>> TRIE_CACHE = new HashMap<>();