[Question] how to define propagations of Java lambda functions?

This question is about how to define propagations of Java lambda functions.

Consider a Java map example:
```
HashMap m = ...; // create a map
m.put("k1", taint_source); // add a taint source into the map
m.forEach((k, v) -> sink_f(v)); // enumerate the map items, and pass the values to a sink function
```

Currently, the pulse analysis won't propagate taint_source to v in the lambda function. How can we introduce such a propagation?

Something like the following doesn't work:
```
{ "procedure_regex": "java\\.util\\.\\(Map\\|HashMap\\).*\\.forEach",
"taint_target": ["ArgumentPositions", [0]]
}
```
Is there a work-around?

Thanks!