code: def init_config()
        # Set up logger.
        provided_logger = @config.read('library.logger')
        self.logger = (provided_logger.nil?) ?
            create_default_logger() : provided_logger
  
        # Set up default HTTPI adapter.
        provided_adapter = @config.read('connection.adapter')
        @config.set('connection.adapter', :httpclient) if provided_adapter.nil?
  
        # Make sure Auth param is a symbol.
        symbolize_config_value('authentication.method')
      end
docs: Initializes config with default values and converts existing if required.