Provide all API methods documentation. The current API is not well documented leaving much space to trial and error.
In general only the supported APIs and supported aspects of APIs are documented
In your example, setting the password is not one that is officially supported.
There are as well private APIs used internally by the system which shouldn't be used outside the intended use, as a result not documented.
Official Micro Focus documentation about API only focus on how to use.
It does not include all the methods and options each API has. One has to guess or do trial an error to discover it.
One of the best examples is if you want to add a default password when creating a user. There is no documentation about the format of the field you have to send in the JSON neither as the consequences of setting a password.
After some trials we discovered that we can use the field "Password" and when the password id set no email is send to the user.