According to this documentation for the ant xjc task -
"To specify more than one external binding file at the same time, use a nested element, which has the same syntax as fileset."
In gradle it would look like this:
binding(dir:'src/main/schema'){
include(name:'A.xjb')
include(name:'B.xjb')
}
I think this would also work:
binding(dir:'src/main/schema', includes:'A.xjb,B.xjb')