Add models for commons lang/text's Str[ing]Lookup class

java/ql/test/library-tests/frameworks/apache-commons-lang3/StrLookupTest.java

@@ -0,0 +1,17 @@
+import org.apache.commons.lang3.text.StrLookup;
+import java.util.HashMap;
+import java.util.Map;
+
+class StrLookupTest {
+    String taint() { return "tainted"; }
+
+    void sink(Object o) {}
+
+    void test() throws Exception {
+      Map<String, String> map = new HashMap<String, String>();
+      map.put("key", taint());
+      StrLookup<String> lookup = StrLookup.mapLookup(map);
+      sink(lookup.lookup("key")); // $hasTaintFlow=y
+    }
+
+}