Gradle is not place WebJar contents into the correct place in my Jar file

I've got a basic Java application in which I would like to use WebJars. I use Gradle as my build system. I would like to use the WebJars for Bootstrap and JQuery so I can easily reference and update them in my Spring-Boot/ThymeLeaf application. The application is basically the one from the form tutorial located here

As I understand it Gradle should place all the files from the WebJars into the META-INF folder in my Jar file. If I understand everything correctly the Spring-Boot resource handler will then load resource from META-INF/ when I reference something in my html page that starts with /webjars/

Unfortunately this doesn't work (yet). Since I see in Tomcat's log output that the resource handler is correctly installed. I decided to check if the files are actually in my Jar file.

When I extract my Jar file the META-INF folder only has a file called MANIFEST.MF with some information about Spring Boot. There is a BootStrap-3.3.7.Jar and a JQuery-3.2-1.Jar file in BOOT-INF/lib but I don't think that is where they are supposed to end up. (Or am I wrong and is there error somewhere in the resource handler?).

How do I tell gradle to do the right thing with these files when I run gradle build?

My gradle.build file looks like this:

buildscript {
    ext {
        springBootVersion = '1.5.8.RELEASE'
    }
    repositories {
        mavenCentral()      
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")        
    }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'
apply plugin: "jacoco"

jar {
    baseName = 'gs-serving-web-content'
    version =  '0.0.1'
}

bootRun {
    addResources = true
}

repositories {
    mavenCentral()  
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

dependencies {
    compile("org.springframework.boot:spring-boot-starter-thymeleaf")
    compile("org.webjars:jquery:3.2.1")
    compile("org.webjars:bootstrap:3.3.7")
    testCompile("org.springframework.boot:spring-boot-starter-test")
}   

Gradle is doing the right thing as the jars should be packaged in BOOT-INF/lib. The root of each jar in BOOT-INF/lib is then added to the classpath from where each its webjar related content in META-INF content should be found.

I'd recommend asking another question that focuses on what your application's doing at runtime. As far as I can tell, everything's working as it should at build time.