Fat jar from scala project throws error when run - scala

Question

I created Scala project using Maven as build tools. I try to build fat jar that later I will be able to run from command line. I wrote a program that use Keycloak library to create users with REST API. It works fine when I run it straight from the Intellij but when I compile and run jar it gives me following error which I assume is result of me misconfiguring maven and not including all required dependencies?
Exception in thread "main" javax.ws.rs.ProcessingException: RESTEASY004655: Unable to invoke request: javax.ws.rs.ProcessingException: RESTEASY003215: could not find writer for content-type application/x-www-form-urlencoded type: javax.ws.rs.core.Form$1
at org.jboss.resteasy.client.jaxrs.engines.ApacheHttpClient4Engine.invoke(ApacheHttpClient4Engine.java:328)
[...]
My pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.generator</groupId>
<artifactId>data-generator</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<exec.mainClass>com.generator.GeneratorApp</exec.mainClass>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<encoding>UTF-8</encoding>
<scala.version>2.13.8</scala.version>
</properties>
<dependencies>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>${scala.version}</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.keycloak</groupId>
<artifactId>keycloak-admin-client</artifactId>
<version>18.0.2</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>42.4.0</version>
<scope>compile</scope>
</dependency>
</dependencies>
<build>
<sourceDirectory>src/main/scala</sourceDirectory>
<plugins>
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<version>3.3.2</version>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>testCompile</goal>
</goals>
<configuration>
<args>
<arg>-dependencyfile</arg>
<arg>${project.build.directory}/.scala_dependencies</arg>
</args>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.21.0</version>
<configuration>
<skipTests>true</skipTests>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.4</version>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.generator.GeneratorApp</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
And commands I am using to compile and run:
mvn clean compile assembly:single
java -cp ./target/data-generator-1.0-SNAPSHOT-jar-with-dependencies.jar com.generator.GeneratorApp
My experience with Maven is very limited (usually i was using SBT when working with Scala). I googled and searched through StackOverflow but I am stuck on this for some time now.
Let me know if you need any more details. I tried to include everything I thought is relevant.

Answer 1

In my case, to fix it, I had to include following dependencies in pom.xml:
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jaxrs</artifactId>
<version>3.13.2.Final</version>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jaxb-provider</artifactId>
<version>3.13.2.Final</version>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jackson2-provider</artifactId>
<version>3.13.2.Final</version>
</dependency>
Not sure why I need it, I thought they would be included automatically based on my other dependencies (Keycloak), which makes me think that it is workaround not actual solution.