demoFinal.java

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;

import java.util.*;

public class Main3 {

    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();

        JsonNode types = mapper.readTree(Main3.class.getClassLoader()
                .getResourceAsStream("original.json"));

        JsonNode postTypes = mapper.readTree(Main3.class.getClassLoader()
                .getResourceAsStream("reference.json"));

        types.forEach(info -> {             // foreach Info in original original.json
            postTypes.forEach(newInfo -> {  // foreach Info in new update reference.json

                if (Objects.equals(info.get("type"), newInfo.get("type"))) {

                    List<JsonNode> merged = mergeAttributes(
                            (ArrayNode) info.get("attributes"),
                            (ArrayNode) newInfo.get("attributes"));

                    ((ObjectNode) info).putPOJO("attributes", merged);
                }

            });
        });

        System.out.println("final types: " + types);
    }

    private static List<JsonNode> mergeAttributes(ArrayNode originalAttrs, ArrayNode newAttrs) {

        ArrayList<JsonNode> result = new ArrayList<>();

        originalAttrs.forEach(oldAttr ->
                newAttrs.forEach(newAttr -> {
                    if (Objects.equals(newAttr.get("name"), oldAttr.get("name"))) {

                        newAttr.fieldNames().forEachRemaining(field ->
                                // put every new field and value like "displayName" to saved original json
                                ((ObjectNode) oldAttr).set(field, newAttr.get(field))
                        );

                        result.add(oldAttr);
                    }
                })
        );

        return result;
    }

}

Option1.java

public class Test {

    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        InputStream data = Test.class.getClassLoader()
                .getResourceAsStream("original.json");
        InputStream postProcessData = Test.class.getClassLoader()
                .getResourceAsStream("reference.json");

        Set<Info> types =  mapper.readValue(data,
                new TypeReference<Set<Info>>() {
                });
        
        ObjectReader updater = mapper.readerForUpdating(types);
        Set<Info> merged = updater.readValue(postProcessData);
        
        System.out.print(mapper.writeValueAsString(merged));
    }



    public static class Info {
        @JsonProperty("type")
        private String type;

        @JsonProperty("attributes")
        private List<Attribute> attributes = new ArrayList<>();

        public List<Attribute> getAttributes() {
            return attributes;
        }

        public void setAttributes(List<Attribute> attributes) {
            this.attributes = attributes;
        }

        public String getType() {
            return type;
        }

        public void setType(String type) {
            this.type = type;
        }

        @Override
        public boolean equals(Object o) {
            return o instanceof Info &&
                    Objects.equals(((Info) o).type, type);
        }


    }

    public static class Attribute{
        @JsonProperty("name")
        private String name;

        @JsonProperty("validOperators")
        private List<String> validOperators;

        @JsonProperty("displayName")
        private List<String> displayName;

        public List<String> getValidOperators() {
            return validOperators;
        }

        public void setValidOperators(List<String> validOperators) {
            this.validOperators = validOperators;
        }

        public List<String> getDisplayName() {
            return displayName;
        }

        public void setDisplayName(List<String> displayName) {
            this.displayName = displayName;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        @Override
        public boolean equals(Object o) {
            return o instanceof Attribute &&
                    Objects.equals(((Attribute) o).name, name);
        }
    }
}

Option2.java

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;

public class Main3 {

    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();

        JsonNode types = mapper.readTree(Main3.class.getClassLoader()
                .getResourceAsStream("original.json"));

        JsonNode postTypes =  mapper.readTree(Main3.class.getClassLoader()
                .getResourceAsStream("reference.json"));


        types.forEach(info->{
            if (info.get("type").asText().equals("com.person.EmployeeInfo")){
                info.get("attributes").forEach(oldAttr->
                    postTypes.get(0).get("attributes").forEach(newAttr->{
                        if (newAttr.get("name").equals(oldAttr.get("name"))) {
                            ((ObjectNode)oldAttr).set("displayName", newAttr.get("displayName"));
                        }
                    })
                );
        }});

        System.out.println("final types: " + types);
    }
}

Option3.java

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;

public class Main3 {

    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();

        JsonNode types = mapper.readTree(Main3.class.getClassLoader()
                .getResourceAsStream("original.json"));

        JsonNode postTypes =  mapper.readTree(Main3.class.getClassLoader()
                .getResourceAsStream("reference.json"));

      JsonNode postTypeNode = postTypes.get(0);
        ArrayNode postType = (ArrayNode) postTypeNode.get("attributes");

        for (JsonNode domainNode: types) {
            if (domainNode.get("type").asText().equals("com.person.EmployeeInfo")) {
                ArrayNode attributeNodes = (ArrayNode) domainNode.get("attributes");
                for (JsonNode attrNode : attributeNodes) {
                    for (JsonNode attrNodeNew: postType) {
                        if (attrNodeNew.get("name").equals(attrNode.get("name"))) {
                            ((ObjectNode)attrNode).set("displayName", attrNodeNew.get("displayName"));
                        }
                    }
                }
            }
        }

        System.out.println("final types: " + types);
    }
}

UpdatedOption.java

types.forEach(info -> {
    if (info.get("type").asText().equals("com.person.EmployeeInfo")) {
        ArrayList<JsonNode> temp = new ArrayList<JsonNode>();
            
        // do calculations
        info.get("attributes").forEach(oldAttr ->
                postTypes.get(0).get("attributes").forEach(newAttr -> {
                    if (newAttr.get("name").equals(oldAttr.get("name"))) {
                      temp.add(((ObjectNode) oldAttr).set("displayName", newAttr.get("displayName")));
                    }
                })
        );

        // replace attributes with temp
        ((ObjectNode) info).putPOJO("attributes", temp);
    }
});