anchor.diff:  NOTE: `output_directory` is an alias for `outputDir`.
   
   Most `Doxyfile` properties can be used in the configuration closure. By convention all `Doxyfile` properties are 
  -in uppercase, but to keep it gradlesque, they must be lowercase in the configuration closure.
  +in uppercase, but to keep it _gradlesque_, they must be in lowercase in the configuration closure.
   
   [source,groovy]
   ----
  
positive.code: }
  ----
  
  This will result in a deprecation warning being printed.
  
negative.code: 
  If no template is supplied, the build process will call `doxygen -g` to generate a default template.
  
  The output directory is set via `outputDir`. The default output directory, if not supplied, is `${buildDir}/docs/doxygen`.
  
  [source,groovy]
  ----
  