C#: Un-deprecate `PublicCallableParameterFlowSource`

csharp/ql/src/semmle/code/csharp/dataflow/flowsources/PublicCallableParameter.qll

@@ -7,8 +7,6 @@
 import csharp
 
 /**
- * DEPRECATED.
- *
  * A parameter of a public callable, for example `p` in
  *
  * ```
@@ -17,7 +15,7 @@ import csharp
  * }
  * ```
  */
-deprecated class PublicCallableParameterFlowSource extends DataFlow::ParameterNode {
+class PublicCallableParameterFlowSource extends DataFlow::ParameterNode {
   PublicCallableParameterFlowSource() {
     exists(Callable c, Parameter p |
       p = this.getParameter() and

csharp/ql/test/library-tests/dataflow/flowsources/publicparameter/PublicCallableParameterFlowSource.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Specialized;
+
+class PublicCallableParameterFlowSource
+{
+    public void M1(string x, out string y, ref string z)
+    {
+        y = x;
+        y = z;
+    }
+
+    void M2(string x, out string y, ref string z)
+    {
+        y = x;
+        y = z;
+    }
+}

csharp/ql/test/library-tests/dataflow/flowsources/publicparameter/publicCallableParameterFlowSource.expected

@@ -0,0 +1,2 @@
+| PublicCallableParameterFlowSource.cs:6:27:6:27 | x |
+| PublicCallableParameterFlowSource.cs:6:55:6:55 | z |

csharp/ql/test/library-tests/dataflow/flowsources/publicparameter/publicCallableParameterFlowSource.ql

@@ -0,0 +1,5 @@
+import semmle.code.csharp.dataflow.flowsources.PublicCallableParameter
+
+from PublicCallableParameterFlowSource source
+where source.getParameter().fromSource()
+select source