I have solved it by removing other attributes included in the request
below request is working fine:
{
"schemas": [
"urn:ietf:params:scim:schemas:sailpoint:1.0:LaunchedWorkflow",
"urn:ietf:params:scim:schemas:sailpoint:1.0:TaskResult"
],
"urn:ietf:params:scim:schemas:sailpoint:1.0:LaunchedWorkflow": {
"workflowName": "LCM Provisioning",
"input": [
{
"key": "plan",
"value": "<ProvisioningPlan nativeIdentity="101018">
<AccountRequest application="IIQ" op="Modify">
<AttributeRequest name="assignedRoles" op="Remove" value="BR_GAG_GROUP_IT_ServiceManagement">
<entry key="source" value="LCM"/> > ",
"type": "application/xml"
},
{
"key": "targetName",
"value": "101018"
},
{
"key": "targetClass",
"value": "Identity"
},
{
"key": "identityName",
"value": "101018"
},
{
"key": "launcher",
"value": ""
},
{
"key": "flow",
"value": "AccessRequest"
},
{
"key": "cuSNOWticketID",
"value": "RITM0019008"
}
]
}
}