Unable to Save Objectify entity with Map<string,Object> in Embedded classes?

I have an embedded entity that has a Field of type Map<String, Object>.

All keys to the Map Are of type String.

Below is Entity

@Entity
@Index
@Getter @Setter
public class NiftySurveys {
	@Id
	private Long id;
	private List<SurveyQuestions> questions;
	private Long createddate;
	private Long updatedDate;
}

@Getter @Setter
public class SurveyQuestions {
	private String label;
	private String code;
	private SurveyQuestionGroups questionGroup;
	private Map<String,Object> optionGroup;
}

>I am having trouble saving Entity with optionGroup.

Sample Entity submitted From FrontEnd

{
	"questions": [{
		"label": "jio",
		"code": null,
		"questionGroup": {
			"name": "Date Time",
			"value": "DATI"
		},
		"optionGroup": {
			"labels": [{
				"label": "Date / Time"
			}],
			"collectDateInfo": true,
			"collectTimeInfo": true,
			"dateFormat": "MM/DD/YYYY",
			"validationMessage": "Please Enter a Valid Date!"
		}
	}, {
		"code": null,
		"label": "Q2",
		"questionGroup": {
			"name": "Multiple Choice Questions",
			"value": "MCQ"
		},
		"optionGroup": {
			"name": "Agree - Disagree",
			"code": "AGDAG",
			"options": [{
				"label": "YES",
				"value": "Y"
			}, {
				"label": "NO",
				"value": "N"
			}]
		}
	}]
}

> All Keys of the map Are Strings.

Error Message:

exception: "com.googlecode.objectify.SaveException"
message: "Error saving com.nifty.niftyfeedbacks.domain.NiftySurveys@4ac88d5e: java.lang.IllegalStateException: Embedded Map keys must be of type String/Enum/Key<?> or field must specify @Stringify"

link to Stack Trace
https://drive.google.com/file/d/1fqpPLiJutWLif5GnrlqLEZ6Wr_PdLdC-/view?usp=sharing

To see how @Stringify works, look at https://github.com/objectify/objectify/wiki/Entities#stringify :

In order to use non-String keys with Maps, you may specify the @Stringify annotation:

import com.googlecode.objectify.annotation.Entity;
import com.googlecode.objectify.annotation.Id;
import com.googlecode.objectify.annotation.Stringify;
import com.googlecode.objectify.stringifier.Stringifier;

class DateStringifier implements Stringifier<LocalDate> {
    @Override
    public String toString(LocalDate obj) {
        return obj.getString();
    }

    @Override
    public LocalDate fromString(String str) {
        return new LocalDate(str);
    }
}

@Entity
class Car {
    @Id Long id;
    @Stringify(DateStringifier.class)
    Map<LocalDate, ServiceRecord> serviceHistory = new HashMap<>();
}

Previous response :
The error message is clear : you must provide a "String-way" to handle your embedded entity. So you should write a toString() method inside your embedded entity or use the @Stringify annotation as appropriate.

It seems to be JSON, so did you try to use @JsonUnwrapped :
@see https://stackoverflow.com/a/10077262/390462

class Item {
    private String title;

    @JsonProperty("date")
    private Date createdAt;

    // How to map this?
    @JsonUnwrapped
    private Author author;
}

You can go through a good JPA tutorial to handle Embedded objects too :

1. https://examples.javacodegeeks.com/enterprise-java/jpa/jpa-embedded-embeddable-example/
2. https://www.logicbig.com/tutorials/java-ee-tutorial/jpa/embeddable-classes.html
3. https://www.tutorialspoint.com/ejb/ejb_embeddable_objects.htm

> Use @Serialize annotation for complex object graph.
From Objectify Docs

This Solved my issue.

@Getter @Setter
public class SurveyQuestions implements Serializable{
	private static final long serialVersionUID = -6930992373082651231L;
	@Serialize
	private Map<String,Object> optionGroup;
	
	
}