Java: Add nullness test covering known FP.

Author: aschackmull

java/ql/test/query-tests/Nullness/B.java

@@ -557,4 +557,23 @@ public void rangetest(int n) {
     if (n > 100) s.hashCode(); // OK
     if (n == 42) s.hashCode(); // OK
   }
+
+  public void testFinally2(int[] xs) {
+    String s = null;
+    int i = 0;
+    while (true) {
+      try {
+        int x = xs[i++];
+        if (x == 0) {
+          s = "foo";
+          break;
+        } else if (x == 1) {
+          continue;
+        }
+      } finally {
+      }
+    }
+    s.hashCode(); // Spurious NPE - false positive
+    // CFG reachability does not distinguish abrupt successors
+  }
 }

java/ql/test/query-tests/Nullness/NullMaybe.expected

@@ -27,6 +27,7 @@
 | B.java:516:5:516:5 | o | Variable $@ may be null at this access as suggested by $@ null guard. | B.java:511:25:511:32 | o | o | B.java:512:22:512:30 | ... == ... | this |
 | B.java:535:7:535:8 | s2 | Variable $@ may be null at this access because of $@ assignment. | B.java:523:5:523:21 | String s2 | s2 | B.java:523:12:523:20 | s2 | this |
 | B.java:537:5:537:6 | s1 | Variable $@ may be null at this access because of $@ assignment. | B.java:522:5:522:21 | String s1 | s1 | B.java:522:12:522:20 | s1 | this |
+| B.java:576:5:576:5 | s | Variable $@ may be null at this access because of $@ assignment. | B.java:562:5:562:20 | String s | s | B.java:562:12:562:19 | s | this |
 | C.java:9:44:9:45 | a2 | Variable $@ may be null at this access as suggested by $@ null guard. | C.java:6:5:6:23 | long[][] a2 | a2 | C.java:7:34:7:54 | ... != ... | this |
 | C.java:9:44:9:45 | a2 | Variable $@ may be null at this access because of $@ assignment. | C.java:6:5:6:23 | long[][] a2 | a2 | C.java:6:14:6:22 | a2 | this |
 | C.java:10:17:10:18 | a3 | Variable $@ may be null at this access as suggested by $@ null guard. | C.java:8:5:8:21 | long[] a3 | a3 | C.java:9:38:9:58 | ... != ... | this |