## Factory Blueprint

### Instructions

You are given an incomplete Factory design pattern implementation with some incorrect parts. Complete and fix the class to demonstrate your understanding of how the Factory design pattern works.

The method `showDetails` should print the class name 'ConcreteProductA' for `ConcreteProductA` and so on.

### Expected Classes

```java
// Product interface
public interface Product {
    void showDetails();
}

// ConcreteProductA class
public class ConcreteProductA {
    ...
}

// ConcreteProductB class
public class ConcreteProductB {
    ...
}

// Factory class
public class Factory {
    public Product createProduct(String type) {

    }
}
```

### Usage

Here is a possible `ExerciseRunner.java` to test your classes:

```java
public class ExerciseRunner {
    public static void main(String[] args) {
        Factory factory = new Factory();

        ConcreteProductA productA = factory.createProduct("A");
        if (productA != null) {
            productA.showDetails();
        } else {
            System.out.println("Invalid product type");
        }

        ConcreteProductA productB = factory.createProduct("B");
        if (productB != null) {
            productB.showDetails();
        } else {
            System.out.println("Invalid product type");
        }

        Object invalidProduct = factory.createProduct("C");
        if (invalidProduct != null) {
            invalidProduct.showDetails();
        } else {
            System.out.println("Invalid product type");
        }
    }
}
```

### Expected Output

```shell
$ javac *.java -d build
$ java -cp build ExerciseRunner
This is ConcreteProductA
This is ConcreteProductB
Invalid product type
$
```