Integration Error "A database constraint was violated while storing the changes in the database."

Summary:

Hi Everyone,
We are testing the 25.1 version of Part Order Integration in Oracle Service Logistics (OFS Sync).
As part of the integration, the integration is calling the following REST API:

/fscmRestApi/resources/latest/partRequirementLines/{requirementLineId}/child/lineDetails

We are sending this payload:
{
"ExpectedArrivalDate": "2025-07-23T07:00:00+00:00",
"RequirementLineId": 300000019097513,
"SourceId": "",
"SourceOrganizationId": -1,
"SourceType": "PR"
}
{
"ExpectedArrivalDate" : "2025-07-24T07:00:00+00:00",
"RequirementLineId" : 300000018976654,
"SourceId" : "",
"SourceOrganizationId" : 300000002332970,
"SourceType" : "TO"
}
But the integration is failing with an error. The error message says:
"A database constraint was violated while storing the changes in the database."
please Let us know what we are missing in the payload .