Log4j (Groovy 2.5.12)

```
@Documented
@Retention(SOURCE)
@Target(TYPE)
public @interface Log4j
```
This local transform adds a logging ability to your program using Log4j logging. Every method call on a unbound variable named log will be mapped to a call to the logger. For this a log field will be inserted in the class. If the field already exists the usage of this transform will cause a compilation error. The method name will be used to determine what to call on the logger.
```
 log.name(exp)
 
```
is mapped to
```
 if (log.isNameEnabled() {
    log.name(exp)
 }
```
Here name is a place holder for info, debug, warning, error, etc. If the expression exp is a constant or only a variable access the method call will not be transformed. But this will still cause a call on the injected logger.
Since:

1.8.0

- Optional Element Summary
  
  Optional Elements
  Modifier and Type Optional Element Description
  
  String category
  
  Class<? extends LogASTTransformation.LoggingStrategy> loggingStrategy
  
  String value

- Element Detail
  - value
```
String value
```
    Default:
    
    "log"
- - category
```
String category
```
    Default:
    
    "##default-category-name##"
- - loggingStrategy
```
Class<? extends LogASTTransformation.LoggingStrategy> loggingStrategy
```
    Default:
    
    groovy.util.logging.Log4j.Log4jLoggingStrategy.class