Attributes
| Name | Required | Default | Description | Examples |
|---|---|---|---|---|
| defaultValue | false | - | The value if the exchange property is null. Defaults to "-" | - |
| expression | true | - | The SPEL expression to access the property on an ExchangeEvaluationContext Using camelCased headers like camelHeader will resolve to camel-header if the camelHeader is not present. | - |
| name | true | - | The key which can be used to access this value in log4j2.xml like %X{key} | - |