Java Jackson Object Patcher

ObjectPatcher.java

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import cz.monetplus.mep.fs.common.jackson.JacksonMapper;
import lombok.SneakyThrows;
import lombok.experimental.UtilityClass;

import java.util.Iterator;
import java.util.Map;
import java.util.Optional;

@UtilityClass
public class ObjectPatcher {

    @SneakyThrows
    public static <T> Optional<T> patch(T obj, T patch, Class<T> clazz) {
        JsonNode objNode = JacksonMapper.DEFAULT.valueToTree(obj);
        JsonNode patchNode = JacksonMapper.DEFAULT.valueToTree(patch);

        boolean modified = patchJsonNode(objNode, patchNode);

        T mergedObj = modified ? JacksonMapper.DEFAULT.convertValue(objNode, clazz) : null;

        return Optional.ofNullable(mergedObj);
    }

    static boolean patchJsonNode(JsonNode obj, JsonNode patch) {
        boolean modified = false;
        if (patch.isObject()) {
            Iterator<Map.Entry<String, JsonNode>> it = patch.fields();
            while (it.hasNext()) {
                Map.Entry<String, JsonNode> e = it.next();
                if (e.getValue().isObject()) {
                    if (patchJsonNode(obj.get(e.getKey()), e.getValue())) {
                        modified = true;
                    }
                } else {
                    JsonNode oldNode = ((ObjectNode) obj).get(e.getKey());
                    String oldValue = oldNode == null ? null : oldNode.asText();
                    String newValue = e.getValue().asText();
                    if ((oldValue == null && newValue != null) || newValue.compareTo(oldValue) != 0) {
                        ((ObjectNode) obj).set(e.getKey(), e.getValue());
                        modified = true;
                    }
                }
            }
        }
        return modified;
    }
}