This method needs to be overridden by any useful subclass, so make it abstract

Author: AngledLuffa

src/edu/stanford/nlp/trees/tregex/TregexMatcher.java

@@ -88,8 +88,7 @@ void resetChildIter(Tree tree) {
   /**
    * Resets the matcher to restart search for matching subexpressions
    */
-  void resetChildIter() {
-  }
+  abstract void resetChildIter();
 
   /**
    * Does the pattern match the tree?  It's actually closer to java.util.regex's