in buildSrc/src/main/groovy/HttpUtil.groovy [50:57]
static HttpRequest deleteRequest(url, user, password) {
HttpRequest.newBuilder()
.uri(new URI(url))
.header('Authorization', 'Basic ' + "$user:$password".getBytes('iso-8859-1').encodeBase64())
.header('Content-Type', 'application/json')
.DELETE()
.build()
}