Incorrect validation for disableStartTls when creating SMTP credentials via API

[untitledds]

Bug Description

When creating an SMTP credential via the n8n API at POST {{baseUrl}}/credentials, the request body includes disableStartTls: true along with secure: false. However, the API returns an error indicating that the data is of a prohibited type (object Object). This seems to be due to schema validation issues, especially around the disableStartTls field.
request.body.data does not match allOf schema [subschema 0] with 2 error[s]:,request.body.data does not match allOf schema [subschema 0] with 1 error[s]:,request.body.data is of prohibited type [object Object]
When request In UI the error same

To Reproduce

1. Send a POST request to {{baseUrl}}/credentials with the following JSON body:
   application/json
   {
   "name": "smtp_server",
   "type": "smtp",
   "data": {
   "user": "exampleUser",
   "password": "examplePassword",
   "host": "example.com",
   "port": 443,
   "hostName": "exampleHostName",
   "secure": false,
   "disableStartTls": true
   }
   }
2. Observe the response from the API.

Expected behavior

The SMTP credential should be created successfully. The disableStartTls flag should be allowed when secure is set to false, as per the logic defined in the schema. Additionally, the API should not reject the request due to a type mismatch or schema validation error.

Operating System

n8nio/n8n

n8n Version

1.88.0

Node.js Version

v20.19.0

Database

SQLite (default)

Execution mode

main (default)

[Joffcom]

Hey @untitledds,

We have created an internal ticket to look into this which we will be tracking as "GHC-2198"