"package does not exist" in multimodule build with maven

I have a Spring Boot Project called "Organizer" with 5 Modules:

• application
• backend
• client-api
• core
• discord-bot

Core is a dependency in all other modules. And all modules are dependencies in the "application" module

Whenever I want to run mvn clean install on organizer ir builds everything until it reaches the "discord-bot" module, there it fails saying package net.dragoncoding.organizer.core does not exist meanwhile the IDE shows no errors at all.

When I manually use mvn clean install on all the modules I can build them all and also build the project.

Is there something I am missing here?

IntelliJ Version: IntelliJ IDEA 2023.1.3 (Ultimate Edition) Build #IU-231.9161.38, built on June 20, 2023

EDIT: Here's the Project pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://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>3.1.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>net.dragoncoding</groupId>
    <artifactId>Organizer</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <packaging>pom</packaging>

    <name>Organizer</name>
    <description>Organizer</description>

    <modules>
        <module>application</module>
        <module>client-api</module>
        <module>backend</module>
        <module>discord-bot</module>
        <module>core</module>
    </modules>

    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.xerial</groupId>
            <artifactId>sqlite-jdbc</artifactId>
            <version>3.42.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate.orm</groupId>
            <artifactId>hibernate-community-dialects</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>net.dragoncoding.organizer.app.Application</mainClass>
                    <executable>true</executable>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

Here the pom.xml for the core module:

<?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>net.dragoncoding</groupId>
        <artifactId>Organizer</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <artifactId>core</artifactId>

    <properties>
        <maven.compiler.source>19</maven.compiler.source>
        <maven.compiler.target>19</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

</project>

And here the pom.ml for the discord-bot module:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://maven.apache.org/POM/4.0.0"
         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>net.dragoncoding</groupId>
        <artifactId>Organizer</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <artifactId>discord-bot</artifactId>

    <properties>
        <maven.compiler.source>19</maven.compiler.source>
        <maven.compiler.target>19</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>net.dragoncoding</groupId>
            <artifactId>core</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>net.dragoncoding</groupId>
            <artifactId>client-api</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>net.dv8tion</groupId>
            <artifactId>JDA</artifactId>
            <version>5.0.0-beta.11</version>
            <exclusions>
                <exclusion>
                    <groupId>club.minnced</groupId>
                    <artifactId>opus-java</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

</project>

Move the whole <build> node from the root Organizer module's POM file to the application sub-module's POM file.

What is happening is by defining spring-boot-maven-plugin:repackage in the root POM, every sub-module inherits it. So the core sub-module dutifully executes this repackage goal, and re-arranges the classes in the JAR to something to be started from the command line. This is why the compiler cannot find anything in net.dragoncoding.organizer.core. What you really want is only the application sub-module to be re-packaged so it is runnable from the command line.

Examine the contents of the core jar file before and after this change by doing a jar tf ~/.m2/repository/net/dragoncoding/core/0.0.1-SNAPSHOT/core-0.0.1-SNAPSHOT.jar. Notice how the org/dragoncoding classes are now at the root instead of under BOOT-INF/classes.

HTH.