Asciidoctor Gradle Plugin Question

when i run asciidoctor from command line, i use

-a icons

to get the actual pix icons to show up in the generate html.

How do i achive that using the asciidoctor closure syntax in a gradle build script pls ?

Also is there a complete list of all the choices we have in this asciidcotor closure ? options, attributes, etc. as i get the feeling the spellings may differ from the asciidoctor gem

thx