Set clientId on create #778

Checklist

• I have looked into the Readme and Examples, and have not found a suitable solution or answer.
• I have looked into the API documentation and have not found a suitable solution or answer.
• I have searched the issues and have not found a suitable solution or answer.
• I have searched the Auth0 Community forums and have not found a suitable solution or answer.
• I agree to the terms within the Auth0 Code of Conduct.

Describe the problem you'd like to have solved

The Auth0 Management API supports setting the client_id field on a Client to a custom value, so long as it conforms to the format requirements, during create. The value then becomes immutable per the spec.
This SDK does not support setting the clientId field on the Client class at all.

Describe the ideal solution

Developers should be able to set the clientId field during object construction. After construction the field should be immutable.

Alternatives and current workarounds

Java reflections can be used to set the value after construction but before calling the Management API.

Field clientIdField = Client.class.getDeclaredField("clientId");
clientIdField.setAccessible(true);
clientIdField.set(client, id);

Additional context

No response