SomeType.java

@Json( style = Style.RAILS, name="sometype")
class SomeType
{
    public String id;
    public String name;
}

SomeTypes.java

class SomeTypes {
    List<SomeType> sometypes;
    public List<SomeType> getSometypes() {
        return sometypes;
    }

    public void setTypes(List<SomeType> t) {
            this.sometypes = t;
    }        
}

sometypes.json

{"sometypes":[{"sometype":{"id":"asd", "name":"me"}}]}

Test.java

class Test {

    static interface SomeTypesEncoder extends JsonEncoderDecoder<SomeTypes>{}
    
    public void testSome(){
        SomeTypesEncoder encoder = GWT.create(SomeTypesEncoder.class);
        SomeTypes s = new SomeTypes();
        SomeType t = new SomeType();
        t.id = "asd";
        t.name = "me";
        s.setTypes(Arrays.asList( t ));
        System.err.println( encoder.encode(s).toString());
    }
}