Return an array of all available attributes of type 'email'. Optionally,
ensure the field is defined in the specified $source.
public static getAvailableEmailFields ( $source = null, $searchable = true ) : array | ||
$source | string An optional source identifier. | |
$searchable | boolean If true, and $source is provided, ensure that the email field is a configured searchable field. | |
리턴 | array | An array of email fields. |