Static and runtime types: Correct Solution

Given the following type declarations:

public class Otchpei {
    public Otchpei kess(Otchpei no) {
        return this;
    }
}

public class SasWoed extends Otchpei {
    public Otchpei kess(Otchpei no) {
        return no;
    }
}

public class Shas extends Otchpei {
    public Otchpei kess(Otchpei no) {
        return new Shas();
    }
}

...and given the following setup code:

SasWoed foo = new SasWoed();
Shas bar = new Shas();

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.kess(foo.kess(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: