From the URLMapping.groovy file:
"/api/v1.0/downloads"(controller: "download", action: "apiList")
"/api/v1.0/download/$version"(controller: "download", action: "apiShow")
"/api/v1.0/publish"(controller:"repository", action:"publish")
"/api/v1.0/publish/$plugin/$version"(controller:"repository", action:"publish")
"/api/v1.0/plugins/$category?"(controller: "plugin", action: "apiList")
"/api/v1.0/plugin/$name/$version"(controller: "plugin") {
action = [GET: "apiShow", PUT: "apiUpdate"]