Changes to kotlin class not recognized by Spring Boot? - eclipse

Question

Changes are not reflected in the service response from http://localhost:8080/hi after:
Modifying the response string of SomeController in the code below
Spring Tool Suite automatically compiles the changes
Spring Boot DevTools automatically restarts the server
Request to http://localhost:8080/hi still gives the old response
Somehow they're getting cached, even after running ./gradlew build manually.
Totally different issues: I have Java 1.8 JRE and JDK installed into two directories under Program Files\Java. The project shows the JRE dependency and running build from STS Gradle Tasks window yields the JRE instead of the JDK, even though JAVA_HOME is properly set to the JDK, STS is configured to use the JDK by default (JRE unchecked), and the Spring Boot Project is configured to use the workspace settings (JDK). It seems to be picking up the JRE from the IDE runtime itself, instead of from the settings? I found a work-around by right-clicking the build task and selecting build -> Open Gradle Run Configuration -> Java Home and manually setting this to the same directory as the JDK. I also found a workaround for the project with right-click on project Properties -> Java Build Path -> Libraries, removing JRE System Library and adding the JDK (Add Library... -> JRE System Library -> Workspace default JRE (jdk1.8.0_144)). But, sometimes the project resets itself to the JRE somehow.
Gradle Distribution: Gradle wrapper from target build
Gradle Version: 4.5.1
Java Home: C:\Program Files\Java\jre1.8.0_171
Code
package com.example.demo
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RestController
#RestController
class SomeController {
#GetMapping("/hi")
fun hi(): String {
return "hey"
}
}
#SpringBootApplication
open class DemoApplication
fun main(args: Array<String>) {
runApplication<DemoApplication>(*args)
}
Configuration
Windows 10 Pro
Spring Tool Suite 3.9.4.RELEASE
JDK 1.8
Kotlin 1.2.41
Gradle Wrapper 4.5.1
Spring Boot + DevTools 2.0.3.RELEASE
Setup Steps
New workspace in STS with Gradle Buildship and Kotlin extensions
Add JDK 1.8 as default
Create project File -> New -> Spring Starter Project
Gradle (Buildship 2.x)
Java 8
Kotlin
Reactive Web
DevTools
Actuator
Right-click project Configure Kotlin -> Add Kotlin Nature
Start service Boot Dashboard -> local -> demo [devtools] [:8080]