Method argument configuration. The corresponding class:org.apache.dubbo.config.ArgumentConfig. This tag is child of <dubbo:method>, which is for feature description of method argument, such as:
| Property | Corresponding URL parameter | Type | Requisite | Default | Effect | Description | Compatibility |
| --- | --- | ---- | --- | --- | --- | --- | --- |
| index | | int | Y | | identification | method name | above 2.0.6 |
| type | | String | Index and type choose one | | identification | Find index of argument by it | above 2.0.6 |
| callback | <metodName><index>.retries | boolean | N | | service governance | Mark whether this argument is a callback service. If true, provider will generate reverse proxy,which can invoke consumer in turn. Generally for event pushing | above 2.0.6 |