Static and runtime types: Correct Solution

Given the following type declarations:

public interface Benglou {
    public Benglou prap(Benglou is);
}

public class Eeppric implements Benglou {
    public Benglou prap(Benglou is) {
        return is;
    }
}

public class Pepea implements Benglou {
    public Benglou prap(Benglou is) {
        return new Pepea();
    }
}

...and given the following setup code:

Pepea foo = new Pepea();
Benglou bar = new Eeppric();

Part 1

Draw an AST for the following expression, labeling the static type (a.k.a. compile-time type) of each node in the tree:

foo.prap(foo).prap(bar)

(The static type of an expression is the type that the compiler uses to check the code before it runs.)

Solution

Part 2

Draw an AST for the same expression, this time labeling the runtime type of each node in the tree.

(The runtime type of an expression is the type of the actual value that appears when the code runs.)

Solution

Related puzzles: