Unable to find tests in Gradle project

[lyneca]

I'm unable to refresh the test explorer window. I'm able to run tests fine from the inline "Run Test" button in the editor, but hitting refresh (or on first loading a project) returns:

Under the Java Test Runner output section:

Error.

Under the Language Support for Java output section

[Error - 12:55:34 AM] Apr 13, 2019 12:55:34 AM Error in calling delegate command handler
null
java.lang.NullPointerException
	at com.microsoft.java.test.plugin.util.TestSearchUtils.searchInPackage(TestSearchUtils.java:344)
	at com.microsoft.java.test.plugin.util.TestSearchUtils.searchTestItems(TestSearchUtils.java:142)
	at com.microsoft.java.test.plugin.handler.TestDelegateCommandHandler.executeCommand(TestDelegateCommandHandler.java:46)
	at org.eclipse.jdt.ls.core.internal.handlers.WorkspaceExecuteCommandHandler$1.run(WorkspaceExecuteCommandHandler.java:151)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.jdt.ls.core.internal.handlers.WorkspaceExecuteCommandHandler.executeCommand(WorkspaceExecuteCommandHandler.java:141)
	at org.eclipse.jdt.ls.core.internal.handlers.JDTLanguageServer.lambda$4(JDTLanguageServer.java:419)
	at org.eclipse.jdt.ls.core.internal.handlers.JDTLanguageServer.lambda$32(JDTLanguageServer.java:803)
	at java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:602)
	at java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:577)
	at java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:443)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

My build.gradle:

/*
 * This file was generated by the Gradle 'init' task.
 *
 * This generated file contains a sample Java project to get you started.
 * For more details take a look at the Java Quickstart chapter in the Gradle
 * User Manual available at https://docs.gradle.org/5.2.1/userguide/tutorial_java_projects.html
 */

plugins {
    // Apply the java plugin to add support for Java
    id 'java'

    // Apply the application plugin to add support for building an application
    id 'application'
}

repositories {
    // Use jcenter for resolving your dependencies.
    // You can declare any Maven/Ivy/file repository here.
    jcenter()
}

dependencies {
    // This dependency is found on compile classpath of this component and consumers.
    implementation 'com.google.guava:guava:27.0.1-jre'

    // Use JUnit test framework
    testImplementation 'junit:junit:4.12'
}

Testing the sample project works fine and is able to find all tests, so let me know if you need more info about my project structure/config.

[lyneca]

Sorry, duplicate of #611