Add missing query_terms impl for TermSetQuery. (#2120)

src/query/set_query.rs

@@ -72,6 +72,14 @@ impl Query for TermSetQuery {
     fn weight(&self, enable_scoring: EnableScoring<'_>) -> crate::Result<Box<dyn Weight>> {
         Ok(Box::new(self.specialized_weight(enable_scoring.schema())?))
     }
+
+    fn query_terms<'a>(&'a self, visitor: &mut dyn FnMut(&'a Term, bool)) {
+        for terms in self.terms_map.values() {
+            for term in terms {
+                visitor(term, false);
+            }
+        }
+    }
 }
 
 struct SetDfaWrapper(Map<Vec<u8>>);