Polish BatchPreparedStatementSetter example in reference manual

Closes gh-24084

Author: sbrannen

src/docs/asciidoc/data-access.adoc

@@ -3848,9 +3848,10 @@ based on entries in a list, and the entire list is used as the batch:
 					"update t_actor set first_name = ?, last_name = ? where id = ?",
 					new BatchPreparedStatementSetter() {
 						public void setValues(PreparedStatement ps, int i) throws SQLException {
-							ps.setString(1, actors.get(i).getFirstName());
-							ps.setString(2, actors.get(i).getLastName());
-							ps.setLong(3, actors.get(i).getId().longValue());
+							Actor actor = actors.get(i);
+							ps.setString(1, actor.getFirstName());
+							ps.setString(2, actor.getLastName());
+							ps.setLong(3, actor.getId().longValue());
 						}
 						public int getBatchSize() {
 							return actors.size();