Since when is it obligated to include an empty constructor in Java?

I was practicing dome Java OO principles, when I encountered with this. I create to POJOs and when trying to make objects from it, if an empty constructor isn't defined, it wont compile.

I find this weird because I used to do that and the JVM included a default one for me. Is it new in Java 7? Am I missing something?

Here is the sample code I made

public class Dog {
String name;
String race;
int age;
/*
public Dog() {
    If this isn't included, it doesn't compile if I try to
    create no-args objects. 
}*/

public Dog (String _name) {
    this.name = _name;
}

public Dog (String _name, String _race) {
    this.name = _name;
    this.race = _race;
}

public Dog (String _name, String _race, int _age) {
    this.name = _name;
    this.race = _race;
    this.age = _age;
}

}