how to map an unconventional JSON payload in OIC passing null for one attribute?

Hi Team,

We need guidance on how to map an unconventional JSON payload in OIC.

We are invoking an external ShipStream REST API which expects a JSON request in the following format (simplified):
{
"jsonrpc": 2.0,
"id": 1234,
"method": "call",
"params": [
null,
"order.create",
[ ... ]
]
}

We have already implemented the required mappings and transformations in the OIC mapper to build this JSON structure. However, we are getting the following error when we try to set xsi:nil="true" in order to send the first params element as null:

Target REST endpoint request payload processing failed.[[ORABPEL-15236
Translation Failure.
Failed to translate XML to JSON. javax.xml.stream.XMLStreamException: Cannot end array: null