Anonymize JSON in Java using JacksonMapper

AnonymizeJson.java

package software.amazon.event.ruler;

import com.fasterxml.jackson.core.JsonProcessingException;
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.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.Function;

public class AnonymizeJSON {

    private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
    private static final Map<String, String> keyToValue = new HashMap<>();
    public static void anonymizeJson(String json) throws JsonProcessingException {
        final JsonNode jsonNode = OBJECT_MAPPER.readTree(json);
        traverseNode(jsonNode, (x) -> {
            if (!keyToValue.containsKey(x)) {
                keyToValue.put(x, generateRandomAlphabeticString(x.length()));
            }
            return keyToValue.get(x);
        });
        System.out.println("\n------------------------------");
        System.out.println(OBJECT_MAPPER.writerWithDefaultPrettyPrinter().writeValueAsString(jsonNode));
        System.out.println("\n------------------------------");
    }

    private static void traverseNode(JsonNode node, Function<String, String> replaceFunc) {
        if(node.isObject()) {
            ObjectNode objectNode = (ObjectNode) node;
            final Iterator<Map.Entry<String, JsonNode>> fields = objectNode.fields();
            while(fields.hasNext()) {
                final Map.Entry<String, JsonNode> next = fields.next();
                final JsonNode childNode = next.getValue();
                if(childNode.isTextual()) {
                    objectNode.put(next.getKey(), replaceFunc.apply(childNode.asText()));
                } else {
                    traverseNode(childNode, replaceFunc);
                }
            }
        } else if(node.isArray()) {
            ArrayNode arrayNode = (ArrayNode) node;
            for(int i=0; i< arrayNode.size(); i++) {
                final JsonNode childNode = arrayNode.get(i);
                if(childNode.isTextual()) {
                    arrayNode.set(i, replaceFunc.apply(childNode.asText()));
                } else {
                    traverseNode(childNode, replaceFunc);
                }
            }
        }
    }

    private static final String ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

    public static String generateRandomAlphabeticString(int length) {
        StringBuilder randomString = new StringBuilder(length);

        for (int i = 0; i < length; i++) {
            int randomIndex = ThreadLocalRandom.current().nextInt(ALPHABET.length());
            char randomChar = ALPHABET.charAt(randomIndex);
            randomString.append(randomChar);
        }

        return randomString.toString();
    }
}