remove unused imports from HelloController

frameworks/Groovy/grails/hello/grails-app/controllers/hello/HelloController.groovy

@@ -1,14 +1,11 @@
 package hello
 
 import grails.converters.JSON
-import grails.transaction.Transactional
 import groovy.transform.CompileStatic
-import groovy.transform.TypeCheckingMode;
 
 import java.util.concurrent.ThreadLocalRandom
 
-import org.springframework.transaction.annotation.Propagation;
-import org.hibernate.Session;
+import org.hibernate.Session
 
 @CompileStatic
 class HelloController {