"no main manifest attribute" while running Jar after building with maven - maven

Question

I have a problem getting a maven build to work properly. It builds just fine, except the Main-Class within the manifest file found in the JAR is not present.
Currently, I have one parrent POM, and one POM for each of two modules. The reactor summary shows a success on all three buils.
However, when I try to run the jar in one of the modules, I am told "no main manifest attribute" exists. Checking the content of the manifest-file within the jar shows the Main-Class is not set:
Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Built-By: user
Created-By: Apache Maven 3.3.9
Build-Jdk: 1.8.0_66
This is the build content of the parrent POM:
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
<executable>${java.compiler}</executable>
<verbose>${java.compiler.verbose}</verbose>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<version>${maven-javadoc-plugin.version}</version>
<configuration>
<quiet>${javadoc.quiet}</quiet>
</configuration>
<executions>
<execution>
<id>attach-javadocs</id>
<phase>package</phase>
<configuration>
<additionalparam>-Xdoclint:none</additionalparam>
</configuration>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
<modules>
<module>ConsolidatedCustomerMasterEndpoint</module>
<module>ConsolidatedCustomerMasterService</module>
</modules>
And this is the build content of the module POM:
<build>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>${spring-boot.version}</version>
<configuration>
<mainClass>no.xyz.ccm.config.CcmApp</mainClass>
<classifier>jetty</classifier>
<requiresUnpack>
<dependency>
<groupId>${project.groupId}</groupId>
<artifactId>CcmService</artifactId>
</dependency>
</requiresUnpack>
<addResources>false</addResources>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>${maven-build-helper-plugin.version}</version>
<executions>
<execution>
<phase>generate-sources</phase>
<goals>
<goal>add-source</goal>
</goals>
<configuration>
<sources>
<source>src/generated/java</source>
</sources>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<version>${maven-resources-plugin.version}</version>
<configuration>
<delimiters>
<delimiter>#</delimiter>
</delimiters>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>