src-openfeign/spring4/README.md

# Feign Spring
This module overrides OpenFeign/feign annotation processing to instead use standard ones supplied by the spring annotations specification.


## Currently Supported Annotation Processing
Feign only supports processing java interfaces (not abstract or concrete classes).

ISE is raised when any annotation's value is empty or null.  Ex. `Path("")` raises an ISE.

Here are a list of behaviors currently supported.
### Type Annotations
#### `@RequestMapping`
Appends the ```value``` to `Target.url()`.  Can have tokens corresponding to `@PathVariable` annotations.
The ```method``` sets the request method.
The ```produces``` adds the first value as the `Accept` header.
The ```consume``` adds the first value as the `Content-Type` header.
### Method Annotations
#### `@RequestMapping`
Appends the value to `Target.url()`.  Can have tokens corresponding to `@PathVariable` annotations.
The method sets the request method.
#### `@GetMapping`
Appends the value to `Target.url()`.  Can have tokens corresponding to `@PathVariable` annotations. 
Sets the `GET` request method. 
#### `@PostMapping`
Appends the value to `Target.url()`.  Can have tokens corresponding to `@PathVariable` annotations.
Sets the `POST` request method. 
#### `@PutMapping`
Appends the value to `Target.url()`.  Can have tokens corresponding to `@PathVariable` annotations.
Sets the `PUT` request method. 
#### `@DeleteMapping`
Appends the value to `Target.url()`.  Can have tokens corresponding to `@PathVariable` annotations.
Sets the `DELETE` request method. 
#### `@PatchMapping`
Appends the value to `Target.url()`.  Can have tokens corresponding to `@PathVariable` annotations.
Sets the `PATCH` request method. 
### Parameter Annotations
#### `@PathVariable`
Links the value of the corresponding parameter to a template variable declared in the path.
#### `@RequestParam`
Links the value of the corresponding parameter to a query parameter.  When invoked, null will skip the query param.