Syntaxt for library definition (transitive = false on string list of dependencies ?)

Hi there,

I would like to configure a section for a library like this

ext {
    libraries = [
        httpcomponents: [ 'org.apache.httpcomponents:httpclient:4.1.2','org.apache.httpcomponents:httpcore:4.1.3','org.apache.httpcomponents:httpmime:4.1.2']
...

What wound be the syntax to specify transitive=false on some of these components ?

Thanks.