Support fully executable jar

Author: kazuki43zoo

pom.xml

@@ -46,6 +46,7 @@
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-maven-plugin</artifactId>
         <configuration>
+          <executable>true</executable>
           <classifier>${repackage.classifier}</classifier>
           <image>
             <builder>paketobuildpacks/builder:tiny</builder>