Add Java stubbing script

Author: joefarebrother

java/ql/src/Stubs/MinimalStubsFromSource.ql

@@ -0,0 +1,27 @@
+/**
+ * Tool to generate C# stubs from a qltest snapshot.
+ *
+ * It finds all declarations used in the source code,
+ * and generates minimal C# stubs containing those declarations
+ * and their dependencies.
+ */
+
+import java
+import Stubs
+
+/** Declarations used by source code. */
+class UsedInSource extends GeneratedDeclaration {
+  UsedInSource() {
+    (
+      this = any(Variable v | v.fromSource()).getType()
+      or
+      this = any(Expr e | e.getEnclosingCallable().fromSource()).getType()
+      or
+      this = any(RefType t | t.fromSource())
+    )
+  }
+}
+
+from GeneratedTopLevel t
+where not t.fromSource()
+select t.getQualifiedName(), t.stubFile()