Java POST to Outbound List API stalls on webhook callback

NICE CXone API & Integrations
1 
{
 "name": "Q4_Outreach_Auto",
 "type": "PREDICTIVE",
 "contactIds": ["c9a8b7-1234-5678-90ab-cdef12345678"],
 "deduplicationMatrix": {"keys": ["phone_number", "email"], "autoRemoveDuplicates": true},
 "dataSource": {"type": "EXTERNAL", "uri": "s3://bucket/contacts.csv"},
 "validationRules": {"phoneNormalization": true, "regulatoryCheck": true},
 "webhookUrl": "https://internal-crm.example.com/gc-sync",
 "auditTrail": true
}

Async list registration job locks up immediately after the CRM WEBHOOKURL callback syncs. Feeding contact ID arrays and DEDUPLICATIONMATRIX keys straight into the DATASOURCE directives. Java HTTP client throws a 422 the second CONCURRENT LIST LIMITS and CONTACT COUNT CONSTRAINTS collide.

Tracking creation latency shows a hard 14-second spike before the autoRemoveDuplicates flag crashes the format verification thread. Local schema validation passes clean every single time. Outbound service flat-out rejects the payload. Thread just dumps. Sticking to GENERAL routing settings, but this registration flow is completely unresponsive.

2

Problem

According to the Genesys Cloud API documentation, the outbound list endpoint does not process webhookUrl parameters during initial creation. The platform architecture dictates that CALLBACK CONFIGURATION must be managed exclusively through PLATFORM EVENT STREAMS. Injecting this parameter directly into the list payload disrupts standard routing settings and bypasses the preferred ADMIN UI workflows.

Code

{
 "name": "Q4_Outreach_Auto",
 "type": "PREDICTIVE",
 "contactIds": ["c9a8b7-1234-5678-90ab-cdef12345678"],
 "dataSource": {
  "type": "EXTERNAL",
  "uri": "s3://bucket/contacts.csv"
 }
}

Error

Retaining the webhook field in the payload causes the Java client to wait indefinitely for a response that will not be generated. The execution thread subsequently hangs on the HTTP connector. Additionally, queue observation metrics will only populate once the CAMPAIGN CONFIGURATION is bound. If the synchronization process fails, dashboard metrics will lag, directly impacting queue analytics and UI layout reporting.

Question

Given the operational requirement to remove the webhook field and utilize the ADMIN UI for LIST CONFIGURATION to attach sync endpoints, what is the standardized procedure to ensure the POST /api/v2/outbound/lists request returns a 202 Accepted status immediately without inducing connector timeouts?