The description of the arguments for FieldDefinition::setDisplayOptions() conflicts with what reported in FieldDefinitionInterface::getDisplayOptions()

FieldDefinition::setDisplayOptions() says that $options should include at least a 'weight', or specify 'type' = 'hidden'.
FieldDefinitionInterface::getDisplayOptions(), instead, says that 'hidden' was a valid value, but it is now deprecated in favor of specifying 'region' => 'hidden'.

The first page should be corrected not to conflict what the last page says.

array $options: An array of display options. Refer to \Drupal\Core\Field\FieldDefinitionInterface::getDisplayOptions() for a list of supported keys. The options should include at least a 'weight', or specify 'region' = 'hidden'. The 'default_widget' / 'default_formatter' for the field type will be used if no 'type' is specified.