Passing nested elements to Ant taskdef failing

Newbe question on calling Ant tasks.

What is the correct way to nest elements for a custom Ant taskdef?

When I try this:

manifest() {

attribute(‘One-Jar-Main-Class’ : mainClassName)


The build fails and I get this error message

  • What went wrong: Execution failed for task ‘:makeOneJar’. > onejar doesn’t support the nested “attribute” element.

The equivalent nest Ant XML works fine with the taskdef. (as an aside, I can’t get Ant code to post here properly)