This plugin automatically generates usernames from users' display names, so users cannot choose their own username.
When a new user signs up, their username is derived from their full name: each word is capitalised and joined, followed by three random digits. For example, "Henk Krol" becomes HenkKrol423.
The username field is hidden from the signup form. The actual username is always set server-side, so it cannot be circumvented by inspecting the form.
Settings:
full_names_enabledenables or disables the plugin.full_names_fallbacksets the base used when the display name produces no valid characters (default:User).