Parse error in UPDATE request

[QSchlegel]

Hello Danube dev team,

while testing the ethr-driver I was able to create a simple DID, however when I was trying to update the DID I got a strange error message:

"Cannot parse UPDATE request (object): Cannot construct instance of `java.util.ArrayList` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('addToDidDocument')
 at [Source: UNKNOWN; byte offset: #UNKNOWN] (through reference chain: uniregistrar.request.UpdateRequest["didDocumentOperation"])"

I used the following simple example in a local uni-registrar instance:

{
           "did": "did:ethr:goerli:0x02c19057a8f4a850b834204ae7f0ff299d03299464ee5fe8d757c15a56213813e8",
           "options": {
             "clientSecretMode": true
           },
           "secret": { },
           "didDocumentOperation": "addToDidDocument",
           "didDocument": {
             "service": [{
               "id": "did:ethr:goerli:0x02c19057a8f4a850b834204ae7f0ff299d03299464ee5fe8d757c15a56213813e8#service-1",
               "type": "DIDCommMessaging",
               "serviceEndpoint": "http://localhost:8080/messaging"
             }]
           }
         }

When looking at the code I did not quiet understand why didDocumentOperation is handled like an Array.

uni-registrar-driver-did-ethr/service/EthrService.ts

Line 80 in 780b3f1

for (const i in didDocumentOperations) {

Best Regards
QS