NoClassDefFoundError when attempting to run unit tests when building Jenkins plugin - maven

Question

I have a custom Jenkins plugin that I've built. I have some test cases that leverage some code out of the jenkins-test-harness project (namely the Junit JenkinsRule.)
Anyway, the unit tests run and pass when I run them in IntelliJ. No exceptions, no errors.
When I try to run them from the Maven commandline, however, all of the tests that rely on the JenkinsRule fail:
[ERROR] testGetLastDate(com.mycompany.myplugin.portlet.utils.UtilsHudsonTest) Time elapsed: 0 s <<< ERROR!
java.lang.NoClassDefFoundError: Could not initialize class org.jvnet.hudson.test.TestPluginManager
at org.jvnet.hudson.test.JenkinsRule.<init>(JenkinsRule.java:325)
at com.mycompany.myplugin.portlet.utils.UtilsHudsonTest.<init>(UtilsHudsonTest.java:19)
That TestPluginManager is in the jenkins-test-harness jar. The JenkinsRule that attempts to call it is right next to it in the same package in the same jar, so clearly the jar itself is successfully on the classpath.
I can't quite figure out why I can't run this job from the commandline using mvn test.
My POM is very simple -- I declare a Parent on the Jenkins plugin-3.2 pom:
<parent>
<groupId>org.jenkins-ci.plugins</groupId>
<artifactId>plugin</artifactId>
<version>3.2</version>
<relativePath/>
</parent>
And I have a dependency on the test harness:
<dependencies>
<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-xml</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>org.jenkins-ci.plugins</groupId>
<artifactId>dashboard-view</artifactId>
<version>${dashboard-view.version}</version>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.jenkins-ci.main</groupId>
<artifactId>jenkins-test-harness</artifactId>
<scope>test</scope>
<version>2.34</version>
</dependency>
</dependencies>
(That's the entire dependencies section, no omissions.)
And in my build section, I only declare the compiler, surefire, and hpi plugins:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.7.0</version>
</plugin>
<plugin>
<groupId>org.jenkins-ci.tools</groupId>
<artifactId>maven-hpi-plugin</artifactId>
<executions>
<execution>
<phase>compile</phase>
<goals>
<goal>hpi</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
</plugin>
</plugins>
</build>
(The surefire config is inherited from the plugin-3.2 parent.)
Here's the bit of the UtilHudsonTest that causes the error -- line 19 is the #Rule annotation:
public class UtilsHudsonTest {
#Rule // This is line 19
public JenkinsRule j = new JenkinsRule();
#Test
public void testGetLastDate() throws Exception {
FreeStyleProject prj = j.createFreeStyleProject("prj1");
prj.scheduleBuild2(0).get();
FreeStyleProject prj2 = j.createFreeStyleProject("prj2");
prj2.scheduleBuild2(0).get();
List<Job> jobs = new ArrayList<>();
jobs.add(prj);
jobs.add(prj2);
LocalDate lastDate = Utils.getLastDate(jobs);
assertNotNull(lastDate);
}
// other tests
}
I'm kind of stumped why this would work in IntelliJ and not in Maven. A mvn dependency:tree shows that the correct and expected dependencies. Any ideas in how to get this plugin to successfully run its test from commandline?