Ejabberd.Config.ValidatorUtility.extract_module_names

You're seeing just the function extract_module_names, go back to Ejabberd.Config.ValidatorUtility module for more information.
Link to this function

extract_module_names(modules)

Specs

extract_module_names(Ejabberd.Config.EjabberdModule.t()) :: [atom()]

Given a list of modules it extracts and returns a list of the module names (which are Elixir.Module).