Fix streams quickstart in Jenkinsfile (#9285)

Jenkinsfile

@@ -50,10 +50,7 @@ def doStreamsArchetype() {
          || { echo 'Could not install kafka-streams.jar (and dependencies) locally`'; exit 1; }
   '''
 
-  sh '''
-    version=`grep "^version=" gradle.properties | cut -d= -f 2` \
-        || { echo 'Could not get version from `gradle.properties`'; exit 1; }
-  '''
+  VERSION = sh(script: 'grep "^version=" gradle.properties | cut -d= -f 2', returnStdout: true).trim()
 
   dir('streams/quickstart') {
     sh '''
@@ -61,23 +58,20 @@ def doStreamsArchetype() {
           || { echo 'Could not `mvn install` streams quickstart archetype'; exit 1; }
     '''
 
-    sh '''
-      mkdir test-streams-archetype && cd test-streams-archetype \
-          || { echo 'Could not create test directory for stream quickstart archetype'; exit 1; }
-    '''
-
-    sh '''
+    dir('test-streams-archetype') {
+      // Note the double quotes for variable interpolation
+      sh """ 
         echo "Y" | mvn archetype:generate \
             -DarchetypeCatalog=local \
             -DarchetypeGroupId=org.apache.kafka \
             -DarchetypeArtifactId=streams-quickstart-java \
-          -DarchetypeVersion=$version \
+            -DarchetypeVersion=${VERSION} \
             -DgroupId=streams.examples \
             -DartifactId=streams.examples \
             -Dversion=0.1 \
             -Dpackage=myapps \
             || { echo 'Could not create new project using streams quickstart archetype'; exit 1; }
-    '''
+      """
 
       dir('streams.examples') {
         sh '''
@@ -87,6 +81,7 @@ def doStreamsArchetype() {
       }
     }
   }
+}
 
 def tryStreamsArchetype() {
   try {