[KoSIT-Validationtool] Validator does not work correctly when packaged as jar within other application

KositValidationDemoApplication.java

package com.example.KositValidationDemo;

import de.kosit.validationtool.api.Check;
import de.kosit.validationtool.api.CheckConfiguration;
import de.kosit.validationtool.impl.DefaultCheck;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.util.ResourceUtils;

import java.io.FileNotFoundException;
import java.net.URI;
import java.net.URISyntaxException;

@SpringBootApplication
public class KositValidationDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(KositValidationDemoApplication.class, args);
    }

    @Bean
    public Check kositValidationCheck() throws FileNotFoundException, URISyntaxException {
        URI scenariosUri = ResourceUtils.toURI(ResourceUtils.getURL("classpath:XRechnung/v1_2/kosit-validation/scenarios.xml"));
        CheckConfiguration checkConfiguration = new CheckConfiguration(scenariosUri);
        return new DefaultCheck(checkConfiguration);
    }
}

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">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.6.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>KositValidationDemo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>KositValidationDemo</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>11</java.version>
		<maven.compiler.target>11</maven.compiler.target>
		<maven.compiler.source>11</maven.compiler.source>
		<maven.build.timestamp.format>yyyyMMdd-HHmm</maven.build.timestamp.format>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<maven.javadoc.skip>true</maven.javadoc.skip>
		<maven.source.skip>true</maven.source.skip>
		<maven.compiler.plugin.version>3.8.1</maven.compiler.plugin.version>
		<maven.enforcer.plugin.version>1.4.1</maven.enforcer.plugin.version>
		<maven.release.plugin.version>2.5.3</maven.release.plugin.version>
		<maven.resources.version>3.1.0</maven.resources.version>
		<org.apache.cxf.version>3.3.0</org.apache.cxf.version>
		<de.kosit.version>v1.0.2</de.kosit.version>
	</properties>

	<repositories>
		<repository>
			<id>jitpack.io</id>
			<url>https://jitpack.io</url>
		</repository>
	</repositories>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.apache.cxf</groupId>
			<artifactId>cxf-xjc-plugin</artifactId>
			<version>${org.apache.cxf.version}</version>
		</dependency>
		<dependency>
			<groupId>com.github.itplr-kosit</groupId>
			<artifactId>validator</artifactId>
			<version>${de.kosit.version}</version>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>
</project>