import io.avaje.jsonb.Json; import io.avaje.jsonb.Jsonb; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import java.text.MessageFormat; import java.util.Map; public class TestNestedGeneric { @Json @Data @AllArgsConstructor @NoArgsConstructor public static class TestMapMap { private Map<String, Map<String, Entity>> dims; @Json @Data @AllArgsConstructor @NoArgsConstructor public static class Entity { private String name; private String value; } } public static void main(String[] args) { var res = new TestMapMap(Map.of("test", Map.of("123", new TestMapMap.Entity("name", "value")))); var jsonb = Jsonb.builder().build(); var p = jsonb.type(TestMapMap.class).toJson(res); System.out.println(p); jsonb.type(TestMapMap.class).fromJson(p).getDims().forEach((k,v)->v.forEach((k2,v2)-> System.out.println(MessageFormat.format("key:{0}, k {1},value:{2}", k,k2, v2)))); } }