private List<T> unmarshallJsonToList(JsonUnmarshallerContext context)
            throws Exception {
        List<T> list = new ArrayList<T>();

        if (context.getCurrentToken() == JsonToken.VALUE_NULL) {
            return null;
        }

        while (true) {
            JsonToken token = context.nextToken();
            if (token == null) {
                return list;
            }

            if (token == END_ARRAY) {
                return list;
            } else {
                list.add(itemUnmarshaller.unmarshall(context));
            }
        }
    }
Unmarshalls the current token in the Json document to list.
aws-java-sdk-core/src/main/java/com/amazonaws/transform/ListUnmarshaller.java