Debugging NICE CXone Flow Variables via API with Java

What You Will Build

• A Java diagnostic utility that extracts flow variable definitions, scope configurations, and data type constraints directly from the CXone Flows API.
• The tool reconstructs variable state during interaction execution by querying the Interactions and Events APIs, validating values against schema rules, and generating execution snapshots.
• The implementation uses Java 17, java.net.http.HttpClient, and Jackson for JSON processing.

Prerequisites

• OAuth 2.0 Client Credentials grant configured in CXone Admin Console
• Required scopes: flows:read, interactions:read, events:read
• Java 17 or later
• Maven dependencies:
  • com.fasterxml.jackson.core:jackson-databind:2.15.2
  • org.slf4j:slf4j-api:2.0.9
  • org.slf4j:slf4j-simple:2.0.9 (for console logging)
• CXone API base URL: https://platform.nicecxone.com (or your environment endpoint)

Authentication Setup

CXone uses OAuth 2.0 Client Credentials flow for machine-to-machine API access. The following code demonstrates token acquisition, TTL caching, and automatic refresh logic.

import com.fasterxml.jackson.databind.JsonNode;
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.util.Base64;
import java.util.concurrent.TimeUnit;

public class CxoneAuth {
    private final String baseUrl;
    private final String clientId;
    private final String clientSecret;
    private final HttpClient client;
    private final ObjectMapper mapper;
    private String accessToken;
    private long tokenExpiryEpoch;

    public CxoneAuth(String baseUrl, String clientId, String clientSecret) {
        this.baseUrl = baseUrl.endsWith("/") ? baseUrl : baseUrl + "/";
        this.clientId = clientId;
        this.clientSecret = clientSecret;
        this.client = HttpClient.newHttpClient();
        this.mapper = new ObjectMapper();
        this.tokenExpiryEpoch = 0;
    }

    public String getAccessToken() throws Exception {
        if (System.currentTimeMillis() < tokenExpiryEpoch - 60000) {
            return accessToken;
        }
        return refreshAccessToken();
    }

    private String refreshAccessToken() throws Exception {
        String credentials = Base64.getEncoder().encodeToString(
            (clientId + ":" + clientSecret).getBytes()
        );
        String body = "grant_type=client_credentials";

        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(baseUrl + "api/v2/oauth/token"))
            .header("Content-Type", "application/x-www-form-urlencoded")
            .header("Authorization", "Basic " + credentials)
            .POST(HttpRequest.BodyPublishers.ofString(body))
            .build();

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

        if (response.statusCode() != 200) {
            throw new RuntimeException("OAuth token request failed: " + response.statusCode() + " " + response.body());
        }

        JsonNode json = mapper.readTree(response.body());
        accessToken = json.get("access_token").asText();
        long expiresIn = json.get("expires_in").asLong();
        tokenExpiryEpoch = System.currentTimeMillis() + (expiresIn * 1000);

        return accessToken;
    }
}

The getAccessToken method enforces a sixty-second safety margin before token expiration. This prevents mid-request authentication failures during long-running event polling operations.

Implementation

Step 1: Retrieve Flow Definition and Parse Variable Schema

The Flows API returns the complete JSON structure of a published flow. Variable definitions reside under the variables array. Each variable object contains name, scope, dataType, nullable, and optionally defaultValue.

Required scope: flows:read
Endpoint: GET /api/v2/flows/{flowId}

import java.util.*;
import com.fasterxml.jackson.databind.JsonNode;
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;

public class CxoneFlowInspector {
    private final CxoneAuth auth;
    private final HttpClient client;
    private final ObjectMapper mapper;

    public record VariableDefinition(String name, String scope, String dataType, boolean nullable, String defaultValue) {}

    public CxoneFlowInspector(CxoneAuth auth) {
        this.auth = auth;
        this.client = HttpClient.newHttpClient();
        this.mapper = new ObjectMapper();
    }

    public Map<String, VariableDefinition> fetchFlowVariables(String flowId) throws Exception {
        String token = auth.getAccessToken();
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(auth.baseUrl + "api/v2/flows/" + flowId))
            .header("Authorization", "Bearer " + token)
            .GET()
            .build();

        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        if (response.statusCode() == 401 || response.statusCode() == 403) {
            throw new SecurityException("Unauthorized or insufficient scopes for flow: " + flowId);
        }
        if (response.statusCode() >= 500) {
            throw new RuntimeException("Server error: " + response.statusCode());
        }

        JsonNode root = mapper.readTree(response.body());
        JsonNode variablesNode = root.path("variables");
        Map<String, VariableDefinition> schema = new LinkedHashMap<>();

        if (variablesNode.isArray()) {
            for (JsonNode var : variablesNode) {
                schema.put(var.get("name").asText(), new VariableDefinition(
                    var.get("name").asText(),
                    var.get("scope").asText("interaction"),
                    var.get("dataType").asText("string"),
                    var.get("nullable").asBoolean(false),
                    var.path("defaultValue").isTextual() ? var.get("defaultValue").asText() : null
                ));
            }
        }
        return schema;
    }
}

The response structure uses a flat variables array at the flow root level. The code maps each definition into a type-safe record. Scope values typically return interaction, flow, or queue. Data types include string, number, boolean, datetime, and array.

Step 2: Query Interaction Events and Reconstruct Node Execution Paths

Variable state changes are emitted as interaction events. The Events API returns a chronological array of flow.variable.set, flow.node.started, and flow.interaction.created events. You must paginate through the results using limit and offset.

Required scope: events:read, interactions:read
Endpoint: GET /api/v2/interactions/{interactionId}/events?limit=500&offset=0

import java.util.*;

public record FlowEvent(String eventType, String timestamp, String nodeId, String variableName, Object value) {}

public class CxoneFlowInspector {
    // ... previous code ...

    public List<FlowEvent> fetchInteractionEvents(String interactionId) throws Exception {
        String token = auth.getAccessToken();
        List<FlowEvent> events = new ArrayList<>();
        int offset = 0;
        int limit = 500;

        while (true) {
            HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(auth.baseUrl + "api/v2/interactions/" + interactionId + "/events?limit=" + limit + "&offset=" + offset))
                .header("Authorization", "Bearer " + token)
                .GET()
                .build();

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

            if (response.statusCode() == 429) {
                long retryAfter = Long.parseLong(response.headers().firstValue("Retry-After").orElse("30"));
                Thread.sleep(retryAfter * 1000);
                continue;
            }
            if (response.statusCode() != 200) {
                throw new RuntimeException("Event fetch failed: " + response.statusCode());
            }

            JsonNode root = mapper.readTree(response.body());
            JsonNode eventsArray = root.path("events");
            if (!eventsArray.isArray() || eventsArray.isEmpty()) {
                break;
            }

            for (JsonNode ev : eventsArray) {
                String type = ev.get("type").asText();
                if (type.equals("flow.variable.set") || type.equals("flow.node.started")) {
                    String varName = ev.path("payload").path("variableName").asText(null);
                    Object val = ev.path("payload").path("value") == null ? null : parseValue(ev.path("payload").path("value"));
                    events.add(new FlowEvent(
                        type,
                        ev.get("timestamp").asText(),
                        ev.path("payload").path("nodeId").asText(null),
                        varName,
                        val
                    ));
                }
            }

            offset += limit;
            if (eventsArray.size() < limit) {
                break;
            }
        }
        return events;
    }

    private Object parseValue(JsonNode node) {
        if (node.isNull()) return null;
        if (node.isTextual()) return node.asText();
        if (node.isNumber()) return node.isInt() ? node.asInt() : node.asDouble();
        if (node.isBoolean()) return node.asBoolean();
        return node.asText();
    }
}

The pagination loop respects the limit parameter and terminates when fewer events are returned than requested. The 429 rate-limit response triggers a sleep based on the Retry-After header. Variable values are parsed into native Java types to preserve type fidelity for validation.

Step 3: Validate Variable Values and Apply Fallback Logic

Raw event payloads do not enforce schema constraints. You must validate each assigned value against the flow definition extracted in Step 1. Invalid types, unexpected nulls, or out-of-bound values require fallback resolution.

import java.util.*;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;

public class CxoneFlowInspector {
    // ... previous code ...

    public record ValidatedVariable(String name, Object value, boolean isValid, String validationError) {}

    public List<ValidatedVariable> validateVariables(Map<String, VariableDefinition> schema, List<FlowEvent> events) {
        Map<String, Object> currentState = new LinkedHashMap<>();
        List<ValidatedVariable> results = new ArrayList<>();

        for (FlowEvent ev : events) {
            if (!ev.eventType().equals("flow.variable.set")) continue;
            String varName = ev.variableName();
            VariableDefinition def = schema.get(varName);
            if (def == null) continue;

            Object rawValue = ev.value();
            boolean isValid = true;
            String error = null;

            // Nullability check
            if (rawValue == null && !def.nullable()) {
                isValid = false;
                error = "Non-nullable variable received null";
                rawValue = def.defaultValue() != null ? def.defaultValue() : resolveFallback(def);
            }

            // Type constraint check
            if (isValid) {
                switch (def.dataType()) {
                    case "number":
                        if (!(rawValue instanceof Number)) {
                            isValid = false;
                            error = "Expected number, got " + (rawValue == null ? "null" : rawValue.getClass().getSimpleName());
                            rawValue = def.defaultValue() != null ? parseFallback(def.defaultValue(), "number") : 0;
                        }
                        break;
                    case "boolean":
                        if (!(rawValue instanceof Boolean)) {
                            isValid = false;
                            error = "Expected boolean";
                            rawValue = Boolean.parseBoolean(def.defaultValue());
                        }
                        break;
                    case "datetime":
                        if (rawValue instanceof String) {
                            try {
                                LocalDateTime.parse((String) rawValue, DateTimeFormatter.ISO_LOCAL_DATE_TIME);
                            } catch (DateTimeParseException e) {
                                isValid = false;
                                error = "Invalid datetime format";
                                rawValue = def.defaultValue();
                            }
                        } else {
                            isValid = false;
                            error = "Expected datetime string";
                            rawValue = def.defaultValue();
                        }
                        break;
                }
            }

            currentState.put(varName, rawValue);
            results.add(new ValidatedVariable(varName, rawValue, isValid, error));
        }

        return results;
    }

    private Object resolveFallback(VariableDefinition def) {
        return switch (def.dataType()) {
            case "number" -> 0;
            case "boolean" -> false;
            case "datetime" -> LocalDateTime.now().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
            default -> "";
        };
    }

    private Object parseFallback(String raw, String type) {
        if (raw == null) return resolveFallback(new VariableDefinition("", "", type, true, null));
        return switch (type) {
            case "number" -> Double.parseDouble(raw);
            case "boolean" -> Boolean.parseBoolean(raw);
            default -> raw;
        };
    }
}

The validation logic applies strict type checking after nullability evaluation. When a constraint violation occurs, the system substitutes the configured default value or generates a type-appropriate fallback. This prevents downstream flow execution failures during diagnostic replay.

Step 4: Generate State Snapshots and Correlate with Events

Replay debugging requires temporal state snapshots aligned with node execution boundaries. The following method groups validated variables by timestamp, attaches the originating node ID, and calculates usage metrics.

import java.util.*;
import java.util.stream.Collectors;

public class CxoneFlowInspector {
    // ... previous code ...

    public record StateSnapshot(String timestamp, String nodeId, Map<String, Object> variableState, int validationFailures) {}
    public record DiagnosticReport(List<StateSnapshot> snapshots, Map<String, Long> variableSetCounts, Map<String, Long> validationErrors) {}

    public DiagnosticReport buildDiagnosticReport(Map<String, VariableDefinition> schema, List<FlowEvent> events) {
        List<ValidatedVariable> validations = validateVariables(schema, events);
        Map<String, Object> currentState = new LinkedHashMap<>();
        List<StateSnapshot> snapshots = new ArrayList<>();
        Map<String, Long> setCounts = new HashMap<>();
        Map<String, Long> errorCounts = new HashMap<>();

        // Group events by timestamp for snapshot generation
        Map<String, List<FlowEvent>> eventsByTime = events.stream()
            .filter(e -> e.eventType().equals("flow.variable.set"))
            .collect(Collectors.groupingBy(FlowEvent::timestamp));

        for (Map.Entry<String, List<FlowEvent>> entry : eventsByTime.entrySet()) {
            String ts = entry.getKey();
            String nodeId = entry.getValue().get(0).nodeId();
            int failures = 0;

            for (FlowEvent ev : entry.getValue()) {
                String varName = ev.variableName();
                setCounts.merge(varName, 1L, Long::sum);

                // Find corresponding validation result
                Optional<ValidatedVariable> match = validations.stream()
                    .filter(v -> v.name().equals(varName))
                    .findFirst();

                if (match.isPresent() && !match.get().isValid()) {
                    failures++;
                    errorCounts.merge(varName, 1L, Long::sum);
                }

                if (match.isPresent()) {
                    currentState.put(varName, match.get().value());
                }
            }

            snapshots.add(new StateSnapshot(ts, nodeId, new LinkedHashMap<>(currentState), failures));
        }

        return new DiagnosticReport(snapshots, setCounts, errorCounts);
    }

    public void printReport(DiagnosticReport report) {
        System.out.println("=== CXone Flow Variable Diagnostic Report ===");
        System.out.println("Snapshots: " + report.snapshots().size());
        System.out.println("Variable Set Frequency: " + report.variableSetCounts());
        System.out.println("Validation Errors: " + report.validationErrors());
        System.out.println("\n--- Execution Snapshots ---");
        for (StateSnapshot snap : report.snapshots()) {
            System.out.printf("[%s] Node: %s | Failures: %d | State: %s%n",
                snap.timestamp(), snap.nodeId(), snap.validationFailures(), snap.variableState());
        }
    }
}

The report aggregates temporal state changes, tracks validation failure counts per variable, and outputs a structured diagnostic view. This structure enables developers to trace exactly which node execution triggered an invalid assignment and how the fallback logic resolved it.

Complete Working Example

The following file combines all components into a single executable class. Replace the placeholder credentials and identifiers before execution.

import com.fasterxml.jackson.databind.JsonNode;
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.util.*;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;
import java.util.stream.Collectors;
import java.util.Base64;

public class CxoneFlowVariableInspector {
    private final String baseUrl;
    private final String clientId;
    private final String clientSecret;
    private final HttpClient client;
    private final ObjectMapper mapper;
    private String accessToken;
    private long tokenExpiryEpoch;

    public record VariableDefinition(String name, String scope, String dataType, boolean nullable, String defaultValue) {}
    public record FlowEvent(String eventType, String timestamp, String nodeId, String variableName, Object value) {}
    public record ValidatedVariable(String name, Object value, boolean isValid, String validationError) {}
    public record StateSnapshot(String timestamp, String nodeId, Map<String, Object> variableState, int validationFailures) {}
    public record DiagnosticReport(List<StateSnapshot> snapshots, Map<String, Long> variableSetCounts, Map<String, Long> validationErrors) {}

    public CxoneFlowVariableInspector(String baseUrl, String clientId, String clientSecret) {
        this.baseUrl = baseUrl.endsWith("/") ? baseUrl : baseUrl + "/";
        this.clientId = clientId;
        this.clientSecret = clientSecret;
        this.client = HttpClient.newHttpClient();
        this.mapper = new ObjectMapper();
        this.tokenExpiryEpoch = 0;
    }

    private String getAccessToken() throws Exception {
        if (System.currentTimeMillis() < tokenExpiryEpoch - 60000) {
            return accessToken;
        }
        return refreshAccessToken();
    }

    private String refreshAccessToken() throws Exception {
        String credentials = Base64.getEncoder().encodeToString((clientId + ":" + clientSecret).getBytes());
        String body = "grant_type=client_credentials";
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(baseUrl + "api/v2/oauth/token"))
            .header("Content-Type", "application/x-www-form-urlencoded")
            .header("Authorization", "Basic " + credentials)
            .POST(HttpRequest.BodyPublishers.ofString(body))
            .build();
        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        if (response.statusCode() != 200) {
            throw new RuntimeException("OAuth token request failed: " + response.statusCode());
        }
        JsonNode json = mapper.readTree(response.body());
        accessToken = json.get("access_token").asText();
        long expiresIn = json.get("expires_in").asLong();
        tokenExpiryEpoch = System.currentTimeMillis() + (expiresIn * 1000);
        return accessToken;
    }

    public Map<String, VariableDefinition> fetchFlowVariables(String flowId) throws Exception {
        String token = getAccessToken();
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(baseUrl + "api/v2/flows/" + flowId))
            .header("Authorization", "Bearer " + token)
            .GET()
            .build();
        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        if (response.statusCode() == 401 || response.statusCode() == 403) {
            throw new SecurityException("Unauthorized or insufficient scopes for flow: " + flowId);
        }
        JsonNode root = mapper.readTree(response.body());
        JsonNode variablesNode = root.path("variables");
        Map<String, VariableDefinition> schema = new LinkedHashMap<>();
        if (variablesNode.isArray()) {
            for (JsonNode var : variablesNode) {
                schema.put(var.get("name").asText(), new VariableDefinition(
                    var.get("name").asText(),
                    var.get("scope").asText("interaction"),
                    var.get("dataType").asText("string"),
                    var.get("nullable").asBoolean(false),
                    var.path("defaultValue").isTextual() ? var.get("defaultValue").asText() : null
                ));
            }
        }
        return schema;
    }

    public List<FlowEvent> fetchInteractionEvents(String interactionId) throws Exception {
        String token = getAccessToken();
        List<FlowEvent> events = new ArrayList<>();
        int offset = 0;
        int limit = 500;
        while (true) {
            HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(baseUrl + "api/v2/interactions/" + interactionId + "/events?limit=" + limit + "&offset=" + offset))
                .header("Authorization", "Bearer " + token)
                .GET()
                .build();
            HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
            if (response.statusCode() == 429) {
                long retryAfter = Long.parseLong(response.headers().firstValue("Retry-After").orElse("30"));
                Thread.sleep(retryAfter * 1000);
                continue;
            }
            if (response.statusCode() != 200) {
                throw new RuntimeException("Event fetch failed: " + response.statusCode());
            }
            JsonNode root = mapper.readTree(response.body());
            JsonNode eventsArray = root.path("events");
            if (!eventsArray.isArray() || eventsArray.isEmpty()) break;
            for (JsonNode ev : eventsArray) {
                String type = ev.get("type").asText();
                if (type.equals("flow.variable.set") || type.equals("flow.node.started")) {
                    String varName = ev.path("payload").path("variableName").asText(null);
                    Object val = ev.path("payload").path("value") == null ? null : parseValue(ev.path("payload").path("value"));
                    events.add(new FlowEvent(type, ev.get("timestamp").asText(), ev.path("payload").path("nodeId").asText(null), varName, val));
                }
            }
            offset += limit;
            if (eventsArray.size() < limit) break;
        }
        return events;
    }

    private Object parseValue(JsonNode node) {
        if (node.isNull()) return null;
        if (node.isTextual()) return node.asText();
        if (node.isNumber()) return node.isInt() ? node.asInt() : node.asDouble();
        if (node.isBoolean()) return node.asBoolean();
        return node.asText();
    }

    public List<ValidatedVariable> validateVariables(Map<String, VariableDefinition> schema, List<FlowEvent> events) {
        List<ValidatedVariable> results = new ArrayList<>();
        for (FlowEvent ev : events) {
            if (!ev.eventType().equals("flow.variable.set")) continue;
            String varName = ev.variableName();
            VariableDefinition def = schema.get(varName);
            if (def == null) continue;
            Object rawValue = ev.value();
            boolean isValid = true;
            String error = null;
            if (rawValue == null && !def.nullable()) {
                isValid = false;
                error = "Non-nullable variable received null";
                rawValue = def.defaultValue() != null ? def.defaultValue() : resolveFallback(def);
            }
            if (isValid) {
                switch (def.dataType()) {
                    case "number":
                        if (!(rawValue instanceof Number)) {
                            isValid = false;
                            error = "Expected number";
                            rawValue = def.defaultValue() != null ? parseFallback(def.defaultValue(), "number") : 0;
                        }
                        break;
                    case "boolean":
                        if (!(rawValue instanceof Boolean)) {
                            isValid = false;
                            error = "Expected boolean";
                            rawValue = Boolean.parseBoolean(def.defaultValue());
                        }
                        break;
                    case "datetime":
                        if (rawValue instanceof String) {
                            try { LocalDateTime.parse((String) rawValue, DateTimeFormatter.ISO_LOCAL_DATE_TIME); }
                            catch (DateTimeParseException e) {
                                isValid = false; error = "Invalid datetime format"; rawValue = def.defaultValue();
                            }
                        } else { isValid = false; error = "Expected datetime string"; rawValue = def.defaultValue(); }
                        break;
                }
            }
            results.add(new ValidatedVariable(varName, rawValue, isValid, error));
        }
        return results;
    }

    private Object resolveFallback(VariableDefinition def) {
        return switch (def.dataType()) {
            case "number" -> 0;
            case "boolean" -> false;
            case "datetime" -> LocalDateTime.now().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
            default -> "";
        };
    }

    private Object parseFallback(String raw, String type) {
        if (raw == null) return resolveFallback(new VariableDefinition("", "", type, true, null));
        return switch (type) {
            case "number" -> Double.parseDouble(raw);
            case "boolean" -> Boolean.parseBoolean(raw);
            default -> raw;
        };
    }

    public DiagnosticReport buildDiagnosticReport(Map<String, VariableDefinition> schema, List<FlowEvent> events) {
        List<ValidatedVariable> validations = validateVariables(schema, events);
        Map<String, Object> currentState = new LinkedHashMap<>();
        List<StateSnapshot> snapshots = new ArrayList<>();
        Map<String, Long> setCounts = new HashMap<>();
        Map<String, Long> errorCounts = new HashMap<>();
        Map<String, List<FlowEvent>> eventsByTime = events.stream()
            .filter(e -> e.eventType().equals("flow.variable.set"))
            .collect(Collectors.groupingBy(FlowEvent::timestamp));
        for (Map.Entry<String, List<FlowEvent>> entry : eventsByTime.entrySet()) {
            String ts = entry.getKey();
            String nodeId = entry.getValue().get(0).nodeId();
            int failures = 0;
            for (FlowEvent ev : entry.getValue()) {
                String varName = ev.variableName();
                setCounts.merge(varName, 1L, Long::sum);
                Optional<ValidatedVariable> match = validations.stream().filter(v -> v.name().equals(varName)).findFirst();
                if (match.isPresent() && !match.get().isValid()) {
                    failures++;
                    errorCounts.merge(varName, 1L, Long::sum);
                }
                if (match.isPresent()) currentState.put(varName, match.get().value());
            }
            snapshots.add(new StateSnapshot(ts, nodeId, new LinkedHashMap<>(currentState), failures));
        }
        return new DiagnosticReport(snapshots, setCounts, errorCounts);
    }

    public void printReport(DiagnosticReport report) {
        System.out.println("=== CXone Flow Variable Diagnostic Report ===");
        System.out.println("Snapshots: " + report.snapshots().size());
        System.out.println("Variable Set Frequency: " + report.variableSetCounts());
        System.out.println("Validation Errors: " + report.validationErrors());
        System.out.println("\n--- Execution Snapshots ---");
        for (StateSnapshot snap : report.snapshots()) {
            System.out.printf("[%s] Node: %s | Failures: %d | State: %s%n",
                snap.timestamp(), snap.nodeId(), snap.validationFailures(), snap.variableState());
        }
    }

    public static void main(String[] args) throws Exception {
        String baseUrl = "https://platform.nicecxone.com/";
        String clientId = "YOUR_CLIENT_ID";
        String clientSecret = "YOUR_CLIENT_SECRET";
        String flowId = "YOUR_FLOW_ID";
        String interactionId = "YOUR_INTERACTION_ID";

        CxoneFlowVariableInspector inspector = new CxoneFlowVariableInspector(baseUrl, clientId, clientSecret);
        Map<String, VariableDefinition> schema = inspector.fetchFlowVariables(flowId);
        List<FlowEvent> events = inspector.fetchInteractionEvents(interactionId);
        DiagnosticReport report = inspector.buildDiagnosticReport(schema, events);
        inspector.printReport(report);
    }
}

Compile and run with javac CxoneFlowVariableInspector.java and java CxoneFlowVariableInspector. The tool outputs a chronological variable state trace with validation failure counts and fallback substitutions.

Common Errors & Debugging

Error: 401 Unauthorized or 403 Forbidden on Flow/Events Endpoints

• Cause: The OAuth client lacks the required scopes, or the token expired during execution.
• Fix: Verify the client configuration includes flows:read, interactions:read, and events:read. Ensure the getAccessToken method refreshes the token before each request. The safety margin of sixty seconds prevents mid-operation expiration.

Error: 429 Too Many Requests on Events API

• Cause: CXone enforces strict rate limits on event retrieval, particularly during pagination.
• Fix: The implementation reads the Retry-After header and pauses execution accordingly. If the header is absent, the code defaults to a thirty-second delay. Reduce concurrent inspection requests or increase the pagination offset interval.

Error: Variable Definition Missing from Flow JSON

• Cause: The flow was published with a different version, or the variable scope is restricted to a subflow.
• Fix: Query the specific flow version using the version query parameter on the Flows API endpoint. Subflow variables require separate API calls to the referenced flow ID.

Error: DateTime Validation Fails on Valid Payloads

• Cause: CXone emits datetime values in ISO 8601 format but sometimes includes timezone offsets (Z or +00:00), which LocalDateTime rejects.
• Fix: Replace LocalDateTime with OffsetDateTime or Instant in the validation switch block. Update the formatter to DateTimeFormatter.ISO_OFFSET_DATE_TIME.

Official References

• NICE CXone Flows API Documentation
• NICE CXone Interactions & Events API Documentation
• NICE CXone OAuth 2.0 Client Credentials Guide
• Java HttpClient Documentation