class Demo {
    String s;
    Object foo;

    Demo() {
        init();
    }

    void init() {}
}

FinalClass.java:5: error: [initialization.fields.uninitialized] the constructor does not initialize fields: s, foo
    Demo() {
    ^
FinalClass.java:6: error: [method.invocation.invalid] call to init() not allowed on the given receiver.
        init();
            ^
  found   : @UnderInitialization Demo
  required: @Initialized Demo
2 errors

    Demo() {
        s = "";
        init();
        foo = "";
    }