new capacity bits (#67)

tests/fixtures/xxe/java/SafeXxe.java

@@ -0,0 +1,10 @@
+// Safe: no XML parser sink reached, body just stored.  Used as a baseline
+// to confirm taint-xxe does not fire when the dangerous API is absent.
+import javax.servlet.http.HttpServletRequest;
+
+public class SafeXxe {
+    public String handle(HttpServletRequest req) {
+        String body = req.getParameter("xml");
+        return body.length() > 0 ? body : "empty";
+    }
+}