Fix samples publish

- When going from boot 2.4.x to 2.5.x build didn't get
  fatjar anymore, instead only "plain" jar were published.
- This same thing happened with local install and
  artifactory publish.
- Define bootJar as artifact in sample projects.
- Fixes #994

build.gradle

@@ -534,7 +534,6 @@ project('spring-statemachine-starter') {
 
 configure(sampleProjects()) {
 	apply plugin: 'org.springframework.boot'
-	// as samples are not published, we can use jdk8
 	compileJava {
 		sourceCompatibility = 1.8
 		targetCompatibility = 1.8
@@ -555,6 +554,10 @@ configure(sampleProjects()) {
 		testCompile("org.junit.jupiter:junit-jupiter-engine")
 	}
 	build.dependsOn bootJar
+
+	artifacts {
+		archives bootJar
+	}
 }
 
 project('spring-statemachine-samples-common') {