Fix the definition of `jarjarTaskClassName` issue
diff --git a/gradle/assemble.gradle b/gradle/assemble.gradle
index 923f47d..145b07b 100644
--- a/gradle/assemble.gradle
+++ b/gradle/assemble.gradle
@@ -22,7 +22,7 @@
 
 group = 'org.codehaus.groovy'
 archivesBaseName = 'groovy'
-jarjarTaskClassName = 'org.pantsbuild.jarjar.JarJarTask'
+final jarjarTaskClassName = 'org.pantsbuild.jarjar.JarJarTask'
 
 ext.srcSpec = copySpec {
     from(projectDir) {