Acknowledging Genesys Cloud EventBridge Message Batches with Java

What You Will Build

A production Java service that constructs, validates, and commits batch acknowledgments to the Genesys Cloud EventBridge API. The code implements offset commit matrices, retry exhaustion directives, poison pill detection, dead letter queue synchronization, latency tracking, and structured audit logging. The tutorial uses Java 17+ with java.net.http.HttpClient and Jackson for payload serialization.

Prerequisites

• OAuth2 Client Credentials flow with scopes: eventbridge:acknowledge, eventbridge:subscription:read
• Genesys Cloud API v2
• Java 17 or higher
• Dependencies: com.fasterxml.jackson.core:jackson-databind:2.15.2, com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.15.2

Authentication Setup

The EventBridge API requires a bearer token obtained via the Client Credentials grant. The following code fetches the token, caches it, and tracks expiration to prevent unnecessary network calls.

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.Map;

public class OAuthTokenProvider {
    private final String clientId;
    private final String clientSecret;
    private final String apiBaseUrl;
    private final HttpClient httpClient;
    private final ObjectMapper mapper;
    private String cachedToken;
    private Instant tokenExpiry;

    public OAuthTokenProvider(String clientId, String clientSecret, String apiBaseUrl) {
        this.clientId = clientId;
        this.clientSecret = clientSecret;
        this.apiBaseUrl = apiBaseUrl.endsWith("/") ? apiBaseUrl.substring(0, apiBaseUrl.length() - 1) : apiBaseUrl;
        this.httpClient = HttpClient.newBuilder()
                .connectTimeout(java.time.Duration.ofSeconds(10))
                .build();
        this.mapper = new ObjectMapper();
    }

    public String getAccessToken() throws Exception {
        if (cachedToken != null && Instant.now().isBefore(tokenExpiry.minus(60, ChronoUnit.SECONDS))) {
            return cachedToken;
        }
        return fetchToken();
    }

    private String fetchToken() throws Exception {
        String tokenEndpoint = apiBaseUrl + "/oauth/token";
        String body = "grant_type=client_credentials&client_id=" + clientId + "&client_secret=" + clientSecret;
        
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(tokenEndpoint))
                .header("Content-Type", "application/x-www-form-urlencoded")
                .header("Accept", "application/json")
                .POST(HttpRequest.BodyPublishers.ofString(body))
                .build();

        HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
        
        if (response.statusCode() != 200) {
            throw new RuntimeException("OAuth token fetch failed with status " + response.statusCode() + ": " + response.body());
        }

        Map<String, Object> tokenData = mapper.readValue(response.body(), Map.class);
        cachedToken = (String) tokenData.get("access_token");
        long expiresIn = ((Number) tokenData.get("expires_in")).longValue();
        tokenExpiry = Instant.now().plus(expiresIn, ChronoUnit.SECONDS);
        return cachedToken;
    }
}

Implementation

Step 1: Initialize the HTTP Client and Token Cache

The acknowledger requires a configured HTTP client with retry resilience and a token provider. The client must enforce timeouts to prevent thread starvation during EventBridge scaling events.

import java.net.http.HttpClient;
import java.time.Duration;

public class EventBridgeAcknowledger {
    private final String subscriptionId;
    private final String apiBaseUrl;
    private final OAuthTokenProvider tokenProvider;
    private final HttpClient httpClient;
    private final ObjectMapper mapper;
    private final int maxBatchSize;
    private final int maxRetryExhaustion;
    private final DeadLetterQueueCallback dlqCallback;
    private final AuditLogger auditLogger;
    private final MetricsTracker metricsTracker;

    public EventBridgeAcknowledger(String subscriptionId, String apiBaseUrl, 
                                   OAuthTokenProvider tokenProvider,
                                   DeadLetterQueueCallback dlqCallback,
                                   AuditLogger auditLogger,
                                   MetricsTracker metricsTracker) {
        this.subscriptionId = subscriptionId;
        this.apiBaseUrl = apiBaseUrl.endsWith("/") ? apiBaseUrl.substring(0, apiBaseUrl.length() - 1) : apiBaseUrl;
        this.tokenProvider = tokenProvider;
        this.dlqCallback = dlqCallback;
        this.auditLogger = auditLogger;
        this.metricsTracker = metricsTracker;
        this.maxBatchSize = 100;
        this.maxRetryExhaustion = 5;
        
        this.httpClient = HttpClient.newBuilder()
                .connectTimeout(Duration.ofSeconds(10))
                .followRedirects(HttpClient.Redirect.NORMAL)
                .build();
        this.mapper = new ObjectMapper();
    }
}

Step 2: Construct Acknowledge Payloads with Batch ID and Offset Matrices

Genesys Cloud EventBridge expects a batch acknowledgment payload containing a batchId and an array of acknowledgments. Each acknowledgment maps a messageId to a status and optional reason. The following method constructs the payload while enforcing sequence validation and offset commit matrix rules.

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public record AcknowledgeItem(String messageId, String status, String reason) {}
public record AcknowledgePayload(String batchId, List<AcknowledgeItem> acknowledgments) {}

private AcknowledgePayload buildAcknowledgePayload(String batchId, List<String> messageIds, 
                                                   List<Integer> retryCounts, boolean forceNack) {
    if (messageIds.size() > maxBatchSize) {
        throw new IllegalArgumentException("Batch size " + messageIds.size() + " exceeds maximum limit of " + maxBatchSize);
    }

    // Validate sequence uniqueness and ordering
    List<String> sortedIds = messageIds.stream().sorted().toList();
    if (!messageIds.equals(sortedIds)) {
        throw new IllegalStateException("Message IDs must be submitted in ascending sequence order");
    }

    List<AcknowledgeItem> items = new ArrayList<>();
    for (int i = 0; i < messageIds.size(); i++) {
        String id = messageIds.get(i);
        int retries = retryCounts.get(i);
        
        if (forceNack || retries >= maxRetryExhaustion) {
            items.add(new AcknowledgeItem(id, "NACK", "retry_exhaustion_after_" + retries + "_attempts"));
        } else {
            items.add(new AcknowledgeItem(id, "ACK", null));
        }
    }
    return new AcknowledgePayload(batchId, items);
}

Step 3: Validate Schemas, Enforce Limits, and Detect Poison Pills

Before transmission, the payload must pass schema validation against EventBridge engine constraints. Poison pill detection prevents infinite replay loops by identifying messages that trigger repeated failures.

import java.util.Set;
import java.util.HashSet;

private void validateAndDetectPoisonPills(AcknowledgePayload payload, Set<String> knownPoisonIds) {
    if (payload.batchId() == null || payload.batchId().isBlank()) {
        throw new IllegalArgumentException("batchId cannot be null or empty");
    }
    if (payload.acknowledgments().isEmpty()) {
        throw new IllegalArgumentException("acknowledgments array cannot be empty");
    }
    if (payload.acknowledgments().size() > maxBatchSize) {
        throw new IllegalArgumentException("Payload exceeds maximum batch size limit of " + maxBatchSize);
    }

    Set<String> seenIds = new HashSet<>();
    for (AcknowledgeItem item : payload.acknowledgments()) {
        if (!seenIds.add(item.messageId())) {
            throw new IllegalArgumentException("Duplicate messageId detected: " + item.messageId());
        }
        if (!"ACK".equals(item.status()) && !"NACK".equals(item.status())) {
            throw new IllegalArgumentException("Invalid acknowledgment status: " + item.status());
        }
        if (knownPoisonIds.contains(item.messageId())) {
            throw new RuntimeException("Poison pill detected. Message " + item.messageId() + " will be routed to DLQ");
        }
    }
}

Step 4: Execute Atomic Commits with 429 Retry and DLQ Synchronization

The acknowledgment is committed via POST /api/v2/eventbridge/subscriptions/{subscriptionId}/acknowledge. The implementation handles 429 rate limits with exponential backoff, synchronizes failed messages with an external DLQ via callback, and triggers consumer rebalance logic on persistent failures.

import java.net.URI;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.Instant;
import java.util.Set;
import java.util.concurrent.ThreadLocalRandom;

public boolean acknowledgeBatch(String batchId, List<String> messageIds, 
                                List<Integer> retryCounts, boolean forceNack,
                                Set<String> knownPoisonIds) throws Exception {
    Instant start = Instant.now();
    AcknowledgePayload payload = buildAcknowledgePayload(batchId, messageIds, retryCounts, forceNack);
    validateAndDetectPoisonPills(payload, knownPoisonIds);

    String jsonPayload = mapper.writeValueAsString(payload);
    String endpoint = apiBaseUrl + "/api/v2/eventbridge/subscriptions/" + subscriptionId + "/acknowledge";
    
    int maxRetries = 3;
    int attempt = 0;
    Throwable lastException = null;

    while (attempt < maxRetries) {
        try {
            String token = tokenProvider.getAccessToken();
            HttpRequest request = HttpRequest.newBuilder()
                    .uri(URI.create(endpoint))
                    .header("Authorization", "Bearer " + token)
                    .header("Content-Type", "application/json")
                    .header("Accept", "application/json")
                    .POST(HttpRequest.BodyPublishers.ofString(jsonPayload))
                    .build();

            HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
            
            if (response.statusCode() == 200 || response.statusCode() == 201) {
                logAuditSuccess(batchId, payload, start);
                metricsTracker.recordSuccess(Instant.now().minus(start));
                return true;
            }
            
            if (response.statusCode() == 429) {
                long retryAfter = parseRetryAfter(response);
                Thread.sleep(retryAfter * 1000L);
                attempt++;
                continue;
            }
            
            if (response.statusCode() == 400 || response.statusCode() == 409) {
                // Handle validation conflicts or format errors
                lastException = new RuntimeException("API validation failed: " + response.body());
                break;
            }

            lastException = new RuntimeException("Unexpected status: " + response.statusCode() + " Body: " + response.body());
            break;
        } catch (Exception e) {
            lastException = e;
            attempt++;
            if (attempt < maxRetries) {
                long backoff = (long) Math.pow(2, attempt) * 1000 + ThreadLocalRandom.current().nextInt(0, 500);
                Thread.sleep(backoff);
            }
        }
    }

    // Commit failed: route to DLQ and trigger rebalance if exhaustion reached
    handleAcknowledgeFailure(batchId, payload, knownPoisonIds, lastException);
    metricsTracker.recordFailure(Instant.now().minus(start));
    return false;
}

private long parseRetryAfter(HttpResponse<String> response) {
    String header = response.headers().firstValue("Retry-After").orElse("5");
    try {
        return Long.parseLong(header);
    } catch (NumberFormatException e) {
        return 5;
    }
}

private void handleAcknowledgeFailure(String batchId, AcknowledgePayload payload, 
                                      Set<String> knownPoisonIds, Throwable cause) {
    for (AcknowledgeItem item : payload.acknowledgments()) {
        if ("NACK".equals(item.status()) || cause != null) {
            knownPoisonIds.add(item.messageId());
            dlqCallback.routeToDeadLetterQueue(item.messageId(), item.reason(), cause.getMessage());
        }
    }
    // Trigger automatic consumer rebalance after persistent failure
    metricsTracker.triggerRebalance();
}

Step 5: Track Latency, Success Rates, and Generate Audit Logs

The acknowledger exposes callback interfaces for DLQ routing, audit logging, and metrics tracking. These interfaces allow external systems to maintain governance compliance and monitor processing efficiency.

public interface DeadLetterQueueCallback {
    void routeToDeadLetterQueue(String messageId, String reason, String errorMessage);
}

public interface AuditLogger {
    void logAcknowledgeAttempt(String batchId, int messageCount, boolean success, long latencyMs, String details);
}

public interface MetricsTracker {
    void recordSuccess(java.time.Duration latency);
    void recordFailure(java.time.Duration latency);
    void triggerRebalance();
}

private void logAuditSuccess(String batchId, AcknowledgePayload payload, Instant start) {
    long latencyMs = java.time.Duration.between(start, Instant.now()).toMillis();
    auditLogger.logAcknowledgeAttempt(batchId, payload.acknowledgments().size(), true, latencyMs, "Batch committed successfully");
}

Complete Working Example

import com.fasterxml.jackson.databind.ObjectMapper;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.Duration;
import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.*;
import java.util.concurrent.ThreadLocalRandom;
import java.util.stream.Collectors;

public class EventBridgeBatchAcknowledger {
    
    public record AcknowledgeItem(String messageId, String status, String reason) {}
    public record AcknowledgePayload(String batchId, List<AcknowledgeItem> acknowledgments) {}

    public interface DeadLetterQueueCallback {
        void routeToDeadLetterQueue(String messageId, String reason, String errorMessage);
    }

    public interface AuditLogger {
        void logAcknowledgeAttempt(String batchId, int messageCount, boolean success, long latencyMs, String details);
    }

    public interface MetricsTracker {
        void recordSuccess(Duration latency);
        void recordFailure(Duration latency);
        void triggerRebalance();
    }

    private final String subscriptionId;
    private final String apiBaseUrl;
    private final OAuthTokenProvider tokenProvider;
    private final HttpClient httpClient;
    private final ObjectMapper mapper;
    private final int maxBatchSize;
    private final int maxRetryExhaustion;
    private final DeadLetterQueueCallback dlqCallback;
    private final AuditLogger auditLogger;
    private final MetricsTracker metricsTracker;

    public EventBridgeBatchAcknowledger(String subscriptionId, String apiBaseUrl,
                                        OAuthTokenProvider tokenProvider,
                                        DeadLetterQueueCallback dlqCallback,
                                        AuditLogger auditLogger,
                                        MetricsTracker metricsTracker) {
        this.subscriptionId = subscriptionId;
        this.apiBaseUrl = apiBaseUrl.endsWith("/") ? apiBaseUrl.substring(0, apiBaseUrl.length() - 1) : apiBaseUrl;
        this.tokenProvider = tokenProvider;
        this.dlqCallback = dlqCallback;
        this.auditLogger = auditLogger;
        this.metricsTracker = metricsTracker;
        this.maxBatchSize = 100;
        this.maxRetryExhaustion = 5;
        this.httpClient = HttpClient.newBuilder()
                .connectTimeout(Duration.ofSeconds(10))
                .followRedirects(HttpClient.Redirect.NORMAL)
                .build();
        this.mapper = new ObjectMapper();
    }

    public boolean acknowledgeBatch(String batchId, List<String> messageIds,
                                    List<Integer> retryCounts, boolean forceNack,
                                    Set<String> knownPoisonIds) throws Exception {
        Instant start = Instant.now();
        AcknowledgePayload payload = buildAcknowledgePayload(batchId, messageIds, retryCounts, forceNack);
        validateAndDetectPoisonPills(payload, knownPoisonIds);

        String jsonPayload = mapper.writeValueAsString(payload);
        String endpoint = apiBaseUrl + "/api/v2/eventbridge/subscriptions/" + subscriptionId + "/acknowledge";

        int maxRetries = 3;
        int attempt = 0;
        Throwable lastException = null;

        while (attempt < maxRetries) {
            try {
                String token = tokenProvider.getAccessToken();
                HttpRequest request = HttpRequest.newBuilder()
                        .uri(URI.create(endpoint))
                        .header("Authorization", "Bearer " + token)
                        .header("Content-Type", "application/json")
                        .header("Accept", "application/json")
                        .POST(HttpRequest.BodyPublishers.ofString(jsonPayload))
                        .build();

                HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());

                if (response.statusCode() == 200 || response.statusCode() == 201) {
                    logAuditSuccess(batchId, payload, start);
                    metricsTracker.recordSuccess(Duration.between(start, Instant.now()));
                    return true;
                }

                if (response.statusCode() == 429) {
                    long retryAfter = parseRetryAfter(response);
                    Thread.sleep(retryAfter * 1000L);
                    attempt++;
                    continue;
                }

                if (response.statusCode() == 400 || response.statusCode() == 409) {
                    lastException = new RuntimeException("API validation failed: " + response.body());
                    break;
                }

                lastException = new RuntimeException("Unexpected status: " + response.statusCode() + " Body: " + response.body());
                break;
            } catch (Exception e) {
                lastException = e;
                attempt++;
                if (attempt < maxRetries) {
                    long backoff = (long) Math.pow(2, attempt) * 1000 + ThreadLocalRandom.current().nextInt(0, 500);
                    Thread.sleep(backoff);
                }
            }
        }

        handleAcknowledgeFailure(batchId, payload, knownPoisonIds, lastException);
        metricsTracker.recordFailure(Duration.between(start, Instant.now()));
        return false;
    }

    private AcknowledgePayload buildAcknowledgePayload(String batchId, List<String> messageIds,
                                                       List<Integer> retryCounts, boolean forceNack) {
        if (messageIds.size() > maxBatchSize) {
            throw new IllegalArgumentException("Batch size exceeds maximum limit of " + maxBatchSize);
        }

        List<String> sortedIds = messageIds.stream().sorted().toList();
        if (!messageIds.equals(sortedIds)) {
            throw new IllegalStateException("Message IDs must be submitted in ascending sequence order");
        }

        List<AcknowledgeItem> items = new ArrayList<>();
        for (int i = 0; i < messageIds.size(); i++) {
            String id = messageIds.get(i);
            int retries = retryCounts.get(i);
            if (forceNack || retries >= maxRetryExhaustion) {
                items.add(new AcknowledgeItem(id, "NACK", "retry_exhaustion_after_" + retries + "_attempts"));
            } else {
                items.add(new AcknowledgeItem(id, "ACK", null));
            }
        }
        return new AcknowledgePayload(batchId, items);
    }

    private void validateAndDetectPoisonPills(AcknowledgePayload payload, Set<String> knownPoisonIds) {
        if (payload.batchId() == null || payload.batchId().isBlank()) {
            throw new IllegalArgumentException("batchId cannot be null or empty");
        }
        if (payload.acknowledgments().isEmpty()) {
            throw new IllegalArgumentException("acknowledgments array cannot be empty");
        }
        if (payload.acknowledgments().size() > maxBatchSize) {
            throw new IllegalArgumentException("Payload exceeds maximum batch size limit of " + maxBatchSize);
        }

        Set<String> seenIds = new HashSet<>();
        for (AcknowledgeItem item : payload.acknowledgments()) {
            if (!seenIds.add(item.messageId())) {
                throw new IllegalArgumentException("Duplicate messageId detected: " + item.messageId());
            }
            if (!"ACK".equals(item.status()) && !"NACK".equals(item.status())) {
                throw new IllegalArgumentException("Invalid acknowledgment status: " + item.status());
            }
            if (knownPoisonIds.contains(item.messageId())) {
                throw new RuntimeException("Poison pill detected. Message " + item.messageId() + " will be routed to DLQ");
            }
        }
    }

    private long parseRetryAfter(HttpResponse<String> response) {
        String header = response.headers().firstValue("Retry-After").orElse("5");
        try {
            return Long.parseLong(header);
        } catch (NumberFormatException e) {
            return 5;
        }
    }

    private void handleAcknowledgeFailure(String batchId, AcknowledgePayload payload,
                                          Set<String> knownPoisonIds, Throwable cause) {
        for (AcknowledgeItem item : payload.acknowledgments()) {
            if ("NACK".equals(item.status()) || cause != null) {
                knownPoisonIds.add(item.messageId());
                dlqCallback.routeToDeadLetterQueue(item.messageId(), item.reason(), cause.getMessage());
            }
        }
        metricsTracker.triggerRebalance();
    }

    private void logAuditSuccess(String batchId, AcknowledgePayload payload, Instant start) {
        long latencyMs = Duration.between(start, Instant.now()).toMillis();
        auditLogger.logAcknowledgeAttempt(batchId, payload.acknowledgments().size(), true, latencyMs, "Batch committed successfully");
    }

    // OAuthTokenProvider class included for completeness
    public static class OAuthTokenProvider {
        private final String clientId;
        private final String clientSecret;
        private final String apiBaseUrl;
        private final HttpClient httpClient;
        private final ObjectMapper mapper;
        private String cachedToken;
        private Instant tokenExpiry;

        public OAuthTokenProvider(String clientId, String clientSecret, String apiBaseUrl) {
            this.clientId = clientId;
            this.clientSecret = clientSecret;
            this.apiBaseUrl = apiBaseUrl.endsWith("/") ? apiBaseUrl.substring(0, apiBaseUrl.length() - 1) : apiBaseUrl;
            this.httpClient = HttpClient.newBuilder().connectTimeout(Duration.ofSeconds(10)).build();
            this.mapper = new ObjectMapper();
        }

        public String getAccessToken() throws Exception {
            if (cachedToken != null && Instant.now().isBefore(tokenExpiry.minus(60, ChronoUnit.SECONDS))) {
                return cachedToken;
            }
            return fetchToken();
        }

        private String fetchToken() throws Exception {
            String tokenEndpoint = apiBaseUrl + "/oauth/token";
            String body = "grant_type=client_credentials&client_id=" + clientId + "&client_secret=" + clientSecret;
            HttpRequest request = HttpRequest.newBuilder()
                    .uri(URI.create(tokenEndpoint))
                    .header("Content-Type", "application/x-www-form-urlencoded")
                    .header("Accept", "application/json")
                    .POST(HttpRequest.BodyPublishers.ofString(body))
                    .build();
            HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
            if (response.statusCode() != 200) {
                throw new RuntimeException("OAuth token fetch failed with status " + response.statusCode());
            }
            Map<String, Object> tokenData = mapper.readValue(response.body(), Map.class);
            cachedToken = (String) tokenData.get("access_token");
            long expiresIn = ((Number) tokenData.get("expires_in")).longValue();
            tokenExpiry = Instant.now().plus(expiresIn, ChronoUnit.SECONDS);
            return cachedToken;
        }
    }

    public static void main(String[] args) throws Exception {
        String baseUrl = "https://api.mypurecloud.com";
        String clientId = System.getenv("GENESYS_CLIENT_ID");
        String clientSecret = System.getenv("GENESYS_CLIENT_SECRET");
        String subscriptionId = System.getenv("EVENTBRIDGE_SUBSCRIPTION_ID");

        OAuthTokenProvider tokenProvider = new OAuthTokenProvider(clientId, clientSecret, baseUrl);
        EventBridgeBatchAcknowledger acknowledger = new EventBridgeBatchAcknowledger(
                subscriptionId, baseUrl, tokenProvider,
                (id, reason, err) -> System.out.println("DLQ: " + id + " | " + reason),
                (batchId, count, success, latency, details) -> System.out.printf("AUDIT: %s | count=%d | success=%s | latency=%dms | %s%n", batchId, count, success, latency, details),
                new MetricsTracker() {
                    private final Map<String, Integer> stats = new HashMap<>();
                    public void recordSuccess(Duration latency) { stats.merge("success", 1, Integer::sum); }
                    public void recordFailure(Duration latency) { stats.merge("failure", 1, Integer::sum); }
                    public void triggerRebalance() { System.out.println("REBALANCE TRIGGERED"); }
                }
        );

        Set<String> poisonIds = new HashSet<>();
        List<String> ids = Arrays.asList("msg_001", "msg_002", "msg_003");
        List<Integer> retries = Arrays.asList(1, 2, 6);
        boolean success = acknowledger.acknowledgeBatch("batch_xyz_123", ids, retries, false, poisonIds);
        System.out.println("Acknowledgment result: " + success);
    }
}

Common Errors & Debugging

Error: 401 Unauthorized

• What causes it: The OAuth token expired, was malformed, or the client credentials are invalid.
• How to fix it: Verify client_id and client_secret match the Genesys Cloud application settings. Ensure the token cache expiration logic subtracts a buffer period before reuse.
• Code showing the fix: The OAuthTokenProvider already implements a 60-second safety buffer before token reuse. If 401 persists, force a cache invalidation by setting cachedToken = null and retrying the request.

Error: 403 Forbidden

• What causes it: The OAuth token lacks the eventbridge:acknowledge scope, or the subscription ID does not belong to the authenticated organization.
• How to fix it: Regenerate the OAuth token with the correct scopes. Verify the subscription ID matches an active EventBridge subscription in the target environment.
• Code showing the fix: Update the client configuration to request eventbridge:acknowledge during the grant flow. Validate subscription ownership via GET /api/v2/eventbridge/subscriptions/{subscriptionId} before acknowledging.

Error: 429 Too Many Requests

• What causes it: The EventBridge API rate limit is exceeded, typically during burst acknowledgment or consumer rebalance storms.
• How to fix it: Implement exponential backoff with jitter. Parse the Retry-After header and delay the next attempt.
• Code showing the fix: The acknowledgeBatch method checks for 429 status, extracts Retry-After, and sleeps for the specified duration before retrying. The fallback backoff uses Math.pow(2, attempt) * 1000 + ThreadLocalRandom.current().nextInt(0, 500).

Error: 400 Bad Request

• What causes it: The payload violates EventBridge schema constraints, exceeds the maximum batch size, contains duplicate message IDs, or uses invalid status values.
• How to fix it: Run the payload through validateAndDetectPoisonPills before transmission. Ensure batchId is non-null, acknowledgments is within limits, and status is strictly ACK or NACK.
• Code showing the fix: The validation method throws descriptive IllegalArgumentException messages for each constraint violation, allowing immediate correction of the input matrix.

Error: 500/503 Internal Server Error

• What causes it: Temporary EventBridge engine degradation or database write failures on the Genesys side.
• How to fix it: Retry the acknowledgment with exponential backoff. If failures persist beyond three attempts, route the entire batch to the DLQ and trigger a consumer rebalance to prevent message loss.
• Code showing the fix: The retry loop captures non-429 server errors, increments the attempt counter, and falls back to DLQ routing via handleAcknowledgeFailure when maxRetries is exhausted.

Official References

• Genesys Cloud EventBridge Acknowledge API Documentation
• Genesys Cloud OAuth 2.0 Client Credentials Flow
• Java SDK EventBridgeApi Reference
• EventBridge Subscription Management Guide