class RuboCop::ConfigLoaderResolver

def merge_with_default(config, config_file, unset_nil:)

only cops explicitly disabled in user configuration are disabled.
AllCops:EnabledByDefault is true, it changes the Enabled params so that
only cops from user configuration are enabled. If
AllCops:DisabledByDefault is true, it changes the Enabled params so that
Merges the given configuration with the default one. If 
def merge_with_default(config, config_file, unset_nil:)
  default_configuration = ConfigLoader.default_configuration
  disabled_by_default = config.for_all_cops['DisabledByDefault']
  enabled_by_default = config.for_all_cops['EnabledByDefault']
  if disabled_by_default || enabled_by_default
    default_configuration = transform(default_configuration) do |params|
      params.merge('Enabled' => !disabled_by_default)
    end
  end
  config = handle_disabled_by_default(config, default_configuration) if disabled_by_default
  override_enabled_for_disabled_departments(default_configuration, config)
  opts = { inherit_mode: config['inherit_mode'] || {}, unset_nil: unset_nil }
  Config.new(merge(default_configuration, config, **opts), config_file)
end