const options = {
  method: 'PATCH',
  headers: {
    'x-api-key': '<api-key>',
    'x-api-secret': '<api-key>',
    'x-connector-id': '<api-key>',
    'x-owner-id': '<api-key>',
    'x-session-token': '<api-key>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    invoice: {
      id: '<string>',
      object: 'resourceRef',
      model: '<string>',
      fields: '<unknown>',
      rawResource: '<unknown>',
      remote: {id: '<string>'},
      createdAt: '<string>',
      updatedAt: '<string>'
    },
    item: {
      id: '<string>',
      object: 'resourceRef',
      model: '<string>',
      fields: '<unknown>',
      rawResource: '<unknown>',
      remote: {id: '<string>'},
      createdAt: '<string>',
      updatedAt: '<string>'
    },
    description: '<string>',
    pricePerUnit: 1,
    quantity: 1,
    totalAmount: 1
  })
};

fetch('https://api.runmorph.dev/v1/resources/accountingInvoiceLineItem/{resourceId}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "object": "resource",
  "model": "<string>",
  "id": "<string>",
  "remote": {
    "id": "<string>"
  }
}