public class PubSubDataRetriever {

    // Google Cloud Pub/Sub parameters
    private static final String PUBSUB_PROJECT_ID = 'operating-ethos-414907';
    private static final String PUBSUB_SUBSCRIPTION_ID = 'SalesforceTopic-sub';
    private static final String PUBSUB_ENDPOINT = 'https://pubsub.googleapis.com/v1/projects/' + PUBSUB_PROJECT_ID +
        '/subscriptions/' + PUBSUB_SUBSCRIPTION_ID + ':pull';

    // Google Cloud API credentials
    private static final String GOOGLE_CLOUD_API_KEY = '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';

    // Method to retrieve data from Cloud Pub/Sub
    public static List<Map<String, Object>> getDataFromPubSub() {
        List<Map<String, Object>> pubsubMessages = new List<Map<String, Object>>();

        // Build request JSON body
        String requestBody = '{"returnImmediately": false, "maxMessages": 10}';

        // Create HTTP request
        HttpRequest request = new HttpRequest();
        request.setEndpoint(PUBSUB_ENDPOINT);
        request.setMethod('POST');
        request.setHeader('Authorization', 'Bearer ' + GOOGLE_CLOUD_API_KEY);
        request.setHeader('Content-Type', 'application/json');
        request.setBody(requestBody);

        // Send HTTP request
        Http http = new Http();
        HttpResponse response = http.send(request);

        // Parse response
        if (response.getStatusCode() == 200) {
            Map<String, Object> responseData = (Map<String, Object>) JSON.deserializeUntyped(response.getBody());
            if (responseData.containsKey('receivedMessages')) {
                List<Object> receivedMessages = (List<Object>) responseData.get('receivedMessages');
                for (Object message : receivedMessages) {
                    Map<String, Object> messageData = new Map<String, Object>();
                    Map<String, Object> messageAttributes = (Map<String, Object>) ((Map<String, Object>) message).get('message');
                    String data = (String) messageAttributes.get('data');
                    messageData.put('data', EncodingUtil.base64Decode(data).toString());
                    pubsubMessages.add(messageData);
                }
            }
        } else {
            System.debug('Error retrieving data from Cloud Pub/Sub. Status code: ' + response.getStatusCode());
            System.debug('Response body: ' + response.getBody());
        }

        // Print response body
        System.debug('Response body: ' + response.getBody());

        return pubsubMessages;
    }
}