Why? (Google's GSON library, version 2.4.x, Java8)

example.java

import com.google.gson.Gson;

public class Example
{
    private class FooExample
    {
        public final String exampleString = "foo";
    }

    private class MooExample
    {
        public final String exampleString;

        public MooExample()
        {
            exampleString = "moo";
        }
    }

    public static void main(String [] args)
    {
        final String raw = "{\"exampleString\":\"MODIFIED\"}";
        Gson gson = new Gson();
        FooExample foo = gson.fromJson(raw, FooExample.class);
        MooExample moo = gson.fromJson(raw, MooExample.class);
        System.out.println("Foo:" + foo.exampleString);
        System.out.println("Moo:" + moo.exampleString);
    }
}

I wouldn't expect you to be able to assign data to a final variable twice? Otherwise it would be "kinda sorta final-ish"