Deep Merge a Java Object when the original does not have the value

Utils.java

import java.util.List;
import java.util.Map;

class Utils {
    
    private Utils() {
    }

    @SuppressWarnings({"unchecked", "rawtypes"})
    private static Map deepMerge(Map original, Map newMap) {
        for (Object key : newMap.keySet()) {
            if (newMap.get(key) instanceof Map newChild && original.get(key) instanceof Map originalChild) {
                original.put(key, deepMerge(originalChild, newChild));
            } else if (newMap.get(key) instanceof List newChild && original.get(key) instanceof List originalChild) {
                for (Object each : newChild) {
                    if (!originalChild.contains(each)) {
                        originalChild.add(each);
                    }
                }
            } else {
                original.putIfAbsent(key, newMap.get(key));
            }
        }
        return original;
    }
}