Fix WhenExpr flow

java/ql/lib/semmle/code/java/ControlFlowGraph.qll

@@ -1248,7 +1248,7 @@ private module ControlFlowGraphImpl {
     )
     or
     // When expressions:
-    exists(WhenExpr whenexpr | n = whenexpr |
+    exists(WhenExpr whenexpr |
       n = whenexpr and
       result = first(whenexpr.getBranch(0)) and
       completion = NormalCompletion()

java/ql/lib/semmle/code/java/dataflow/internal/DataFlowUtil.qll

@@ -156,6 +156,8 @@ predicate simpleLocalFlowStep(Node node1, Node node2) {
   or
   node2.asExpr() = any(NotNullExpr nne | node1.asExpr() = nne.getExpr())
   or
+  node2.asExpr().(WhenExpr).getBranch(_).getAResult() = node1.asExpr()
+  or
   exists(MethodAccess ma, ValuePreservingMethod m, int argNo |
     ma.getCallee().getSourceDeclaration() = m and m.returnsValue(argNo)
   |