Running javafx application - Error occurred during initialization of boot layer: java.lang.module.ResolutionException

As the title says, I'm just trying to run the javafx application. However I have no idea why I'm getting this error, and I don't know why the error is referencing the sisu.inject.bean and aopalliance modules. I don't know wether the module-info.java or the pom.xml is causing the error. Thanks in advance for any anwser.

module-info.java:

module ui {
    requires javafx.fxml;
    requires transitive javafx.graphics;
    requires javafx.controls;
    requires org.testfx.junit5;
    requires junit;
    requires core;
    exports ui.java;
    exports test.ui to junit;
}

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<groupId>it1901.nachwithme</groupId>
<artifactId>parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>ui</artifactId>
<dependencies>
<!-- UI imports core as a dependency -->
<dependency>
<groupId>it1901.nachwithme</groupId>
<artifactId>core</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<!-- Dependencies for javafx -->
<dependency>
<groupId>org.openjfx</groupId>
<artifactId>javafx-fxml</artifactId>
</dependency>
<dependency>
<groupId>org.testfx</groupId>
<artifactId>testfx-core</artifactId>
<exclusions>
<exclusion>
<!-- https://mvnrepository.com/artifact/org.sonatype.sisu/sisu-inject-bean -->
<groupId>org.sonatype.sisu</groupId>
<artifactId>sisu-inject-bean</artifactId>
</exclusion>
<exclusion>
<!-- https://mvnrepository.com/artifact/aopalliance/aopalliance -->
<groupId>aopalliance</groupId>
<artifactId>aopalliance</artifactId>
</exclusion>
</exclusions>
</dependency>
<!-- Dependencies for javafx -->
<!-- Dependencies for unit-testing -->
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.openjfx</groupId>
<artifactId>javafx-graphics</artifactId>
<version>16-ea+2</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.testfx</groupId>
<artifactId>testfx-junit5</artifactId>
<scope>compile</scope>
</dependency>
<!-- Dependencies for unit-testing -->
<dependency>
<groupId>org.testng</groupId>
<artifactId>testng</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.jacoco</groupId>
<artifactId>jacoco-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>prepare-agent</goal>
</goals>
</execution>
<execution>
<id>report</id>
<phase>test</phase>
<goals>
<goal>report</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-checkstyle-plugin</artifactId>
</plugin>
<plugin>
<groupId>com.github.spotbugs</groupId>
<artifactId>spotbugs-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.openjfx</groupId>
<artifactId>javafx-maven-plugin</artifactId>
<configuration>
<options>
<!-- <option>dash dash enable-preview</option> -->
</options>
<mainClass>ui.java.App</mainClass>
</configuration>
</plugin>
</plugins>
<sourceDirectory>src</sourceDirectory>
<resources>
<resource>
<directory>src</directory>
<includes>
<include>**/*.fxml</include>
<include>**/*.png</include>
</includes>
</resource>
</resources>
<testSourceDirectory>src/test</testSourceDirectory>
<testResources>
<testResource>
<directory>test</directory>
<includes>
<include>**/*.fxml</include>
<include>**/*.png</include>
</includes>
</testResource>
</testResources>
</build>
</project>

Error:

Error occurred during initialization of boot layer  
java.lang.module.ResolutionException: Modules sisu.inject.bean and aopalliance export package org.aopalliance.aop to module org.testfx
Process finished with exit code 1

TL;DR — The two modules have a split package in common. And JPMS forbids split packages.

The long-winded version

The first sentence of this 2010 blog gives a summary of what a split package is…¹

>> „…A “split package” is a pretty old Java term where you have packages in different libraries with the same name providing related (or sometimes unrelated functionality)…“

Keep in mind that was written in 2010 though; before JPMS. So the blog's claim of „without any problem at both compile and runtime“ in the second sentence is out-of-date; for the modulepath in any case.

For a way more detailed, more up-to-date explanation, watch this Project Jigsaw: Under the Hood video from JavaOne 2016.²

> „…why the error is referencing the sisu.inject.bean and aopalliance modules…“

Because your project has a module descriptor (module-info.java) Maven has put those dependencies — which I can see you declared in your pom — on the modulepath.

> „…However I have no idea why I'm getting this error…“

Because JPMS abhors split packages…³

>> …
>>
>> „There are two issues with split packages,
>> - if you have the same class in each part of the package, the behavior of your
>> [program] depend on the order in the classpath,
>> i've experienced this kind of bugs with two different libraries requiring
>> different version of ASM, at runtime, a class of the older version was calling a
>> class of the newer version
>> - security, if you allow split packages, you allow anybody to insert any classes in any packages.
>>
>> …

The solution

…
<plugin>
    <groupId>org.openjfx</groupId>
    <artifactId>javafx-maven-plugin</artifactId>
    <version>0.0.4</version>
	<configuration>
		<options>
			<option>--patch-module</option>
			<option>org.sonatype.sisu=${env.M2_REPO}/aopalliance/aopalliance/1.0/aopalliance-1.0jar</option>
		</options>
        <mainClass>ui.java.App</mainClass>
	</configuration>
</plugin>
…

<br />
<br />
<br />
<br />
<br />

^¹&nbsp;^{That&nbsp;blog&nbsp;talks&nbsp;about&nbsp;OSGi.&nbsp;But&nbsp;the&nbsp;core&nbsp;split&nbsp;package&nbsp;definition&nbsp;applies&nbsp;to&nbsp;JPMS&nbsp;too.}<br />
^²&nbsp;^{Project&nbsp;Jigsaw:&nbsp;Under&nbsp;The&nbsp;Hood&nbsp;—&nbsp;accompanying&nbsp;slides.}<br />
^³&nbsp;^{Rémi&nbsp;Forax&nbsp;—&nbsp;The&nbsp;split&nbsp;package&nbsp;problem&nbsp;—&nbsp;Jigsaw&nbsp;Dev&nbsp;Mailing&nbsp;List&nbsp;—&nbsp;November&nbsp;2016.}