Remove uses of deprecated Jar.classifier property in build.gradle

build.gradle

@@ -24,12 +24,12 @@ repositories {
 mainClassName = "org.sablecc.sablecc.SableCC"
 
 task javadocJar(type: Jar) {
-  classifier = 'javadoc'
+  archiveClassifier.set("javadoc")
   from javadoc
 }
 
 task sourcesJar(type: Jar) {
-  classifier = 'sources'
+  archiveClassifier.set("sources")
   from sourceSets.main.allSource
 }