Java

public MyObject someMethod(){  
    MyObject localObject = new MyObject();  
    return localObject();  
}

//Another thread can now mutate this object because it has a reference to it:
someMethod.changeSomething();

MyMember member;

public void someMethod(){
    LocalObject localObject = new LocalObject();

    localObject.callMethod();
    method2(localObject);
}

public void method2(LocalObject localObject){
    localObject.setValue("value");
    member = localObject;
}