Issue while setting new Asset password

I'm able to create a new assetaccount however while trying to set the password for that assetaccount facing issue, appreciate any guidance, here are the details:

My call:

connection.invokeMethod(Service.Core, Method.Put, String.format("AssetAccounts/15557/Password"), "testPass", null, null);

com.oneidentity.safeguard.safeguardjava.exceptions.SafeguardForJavaException: Error returned from Safeguard API, Error: 400 {"Code":70000,"Message":"The request is invalid.","ModelState":{"entity.":["Unexpected character encountered while parsing value: e. Path '', line 1, position 1."]}}