Develop Reference

How do I remove Maven Error Aggregator projects require 'pom' as packaging

I've a project with having 3 modules, I work on Intellij with jdk 16. Problem is while doing MVN clean install, I stuck with the following error:
The project org.springbank:user-management:1.0 (B:\spring\user-management\pom.xml) has
1 error [ERROR] 'packaging' with value 'jar' is invalid. Aggregator projects
require 'pom' as packaging. # line 4, column 109
Above error pointing out that parent pom.xml has a problem.
I also mention hereunder my all three pom.xml
pom.xml - Parent
<?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.springbank</groupId>
<artifactId>user-management</artifactId>
<version>1.0</version>
<properties>
<maven.compiler.source>16</maven.compiler.source>
<maven.compiler.target>16</maven.compiler.target>
</properties>
<modules>
<module>user.core</module>
<module>user.cmd.api</module>
<module>user.query.api</module>
</modules>
</project>
pom.xml user.core
<?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
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>2.4.1</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.springbank</groupId>
<artifactId>user.core</artifactId>
<version>1.0.0</version>
<name>user.core</name>
<description>The User Core Project</description>
<properties>
<java.version>16</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</project>
pom.xml user.cmd.api
<?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
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>2.5.3</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.springbank</groupId>
<artifactId>user.cmd.api</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>user.cmd.api</name>
<description>User Command API Project</description>
<properties>
<java.version>16</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<excludes>
<exclude>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
</project>

The error message is pretty clear:
'packaging' with value 'jar' is invalid. Aggregator projects
require 'pom' as packaging. # line 4, column 109
your parent pom should have packaging type pom
<groupId>org.springbank</groupId>
<artifactId>user-management</artifactId>
<version>1.0</version>
<packaging>pom</packaging>

In your parent pom.xml, you need to specify the packaging as being of tap pom since it default to jar while your parent descriptor is intended to aggregate sub-modules:
<?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.springbank</groupId>
<artifactId>user-management</artifactId>
<version>1.0</version>
<packaging>pom</packaging> <!-- set the packaging as pom -->
<properties>
<maven.compiler.source>16</maven.compiler.source>
<maven.compiler.target>16</maven.compiler.target>
</properties>
<modules>
<module>user.core</module>
<module>user.cmd.api</module>
<module>user.query.api</module>
</modules>
</project>

Maven: "Could not find artifact package:jar:1.0-SNAPSHOT"?

I've tried installing a Spring project, and had one created from start.spring.io. However, when trying to run mvn clean install, I have run into errors:
Could not find artifact com.sof:game-mix:jar:1.0-SNAPSHOT
I know this is has happened to others, and I've checked these threads for more information but unfortunately my attempts to replicate their solutions haven't worked for me.
Here is a link to my project, for anyone who wishes to replicate the project and see if mvn clean install might work for them. Otherwise, the code for my pom.xml files is below
I have three pom.xml files:
Root 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>com.sof</groupId>
<artifactId>game-mix</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>
<parent>
<artifactId>spring-boot-starter-parent</artifactId>
<groupId>org.springframework.boot</groupId>
<version>2.0.3.RELEASE</version>
<relativePath/>
</parent>
<modules>
<module>core</module>
<module>web</module>
</modules>
<properties>
<java.version>13</java.version>
</properties>
</project>
My web module's pom.xml:
<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>
<artifactId>game-mix</artifactId>
<groupId>com.sof</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>web</artifactId>
<dependencies>
<!--dependency for our core module-->
<dependency>
<groupId>com.sof</groupId>
<artifactId>game-mix</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
<!--dependency for spring boot-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!--Thymeleaf Dependency-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<!--Spring Boot devtools-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.12</version>
<scope>compile</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
And my core module's 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>
<artifactId>game-mix</artifactId>
<groupId>com.sof</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>core</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
</dependencies>
</project>
Where exactly am I going wrong? I'd appreciate any assistance

I deleted my first answer because I did not read your POMs thoroughly enough.
com.sof:game-mix:jar:1.0-SNAPSHOT is your parent POM. You cannot reference it as a <dependency>.

Maven spring boot multi module project in intellij not building successfully after maven package command

I have a spring boot multi-module project in IntelliJ, The problem is, when I run the project in IntelliJ, it builds and works as expected but when I try a maven package, I get this error:
The POM for ng.biosec:enrollment_ws:jar:0.0.1-SNAPSHOT is missing, no
dependency information available and The POM for
ng.biosec:abis_module:jar:0.0.1-SNAPSHOT is missing, no dependency
information available
and then the process fails.
Here is my pom.xml for the the two modules and the parent:
enrollment_ws.xml pom
<?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>
<artifactId>integron</artifactId>
<groupId>ng.biosec</groupId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>enrollment_ws</artifactId>
<packaging>jar</packaging>
<dependencies>
</dependencies>
</project>
This is the abis_module.xml pom file:
<?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>
<artifactId>integron</artifactId>
<groupId>ng.biosec</groupId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>abis_module</artifactId>
<packaging>jar</packaging>
</project>
This is the cpm.xml pom file that depends on the modules that contain the pom files mentioned above:
<?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>
<artifactId>integron</artifactId>
<groupId>ng.biosec</groupId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>cpm</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>ng.biosec</groupId>
<artifactId>enrollment_ws</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>ng.biosec</groupId>
<artifactId>abis_module</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.springframework.ws</groupId>
<artifactId>spring-ws-core</artifactId>
</dependency>
</dependencies>
</project>
The cpm module contains the Spring boot application class. This is the Spring Application class:
#SpringBootApplication
#EnableScheduling
#EnableJpaRepositories(basePackages = {"integron"})
#ComponentScan(basePackages = {"integron"})
#EntityScan(basePackages = {"integron"})
public class BioConnectApplication {
public static void main(String[] args) {
SpringApplication.run(BioConnectApplication.class, args);
}
}
Also, this is the parent pom file:
<?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>
<modules>
<module>enrollment_ws</module>
<module>cpm</module>
<module>verification</module>
<module>abis_module</module>
</modules>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.1.RELEASE</version>
<relativePath/> <!-- lookup parent from integron.repository -->
</parent>
<groupId>ng.biosec</groupId>
<artifactId>integron</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<name>integron</name>
<description>Bio Connect Project</description>
<properties>
<java.version>1.8</java.version>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<!-- tag::wsdl[] -->
<plugin>
<groupId>org.jvnet.jaxb2.maven2</groupId>
<artifactId>maven-jaxb2-plugin</artifactId>
<version>0.13.1</version>
<executions>
<execution>
<goals>
<goal>generate</goal>
</goals>
</execution>
</executions>
<configuration>
<schemaLanguage>WSDL</schemaLanguage>
<generatePackage>integron.client</generatePackage>
<schemas>
<schema>
<url>********?wsdl</url>
</schema>
</schemas>
</configuration>
</plugin>
<!-- end::wsdl[] -->
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</project>
Also:
I replaced the link to the WSDL file for security reason, but the maven project also does not generate classes from the WSDL. Any help with that will be greatly appreciated.

You should remove the <parent> element declaration from your integron module descriptor and move it to the sub-modules.
The spring-boot-maven-plugin should only be declared within the module holding your Spring Boot application i.e. the cpm module.
Here down how the integron project descriptor should be:
<?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>
<modules>
<module>enrollment_ws</module>
<module>cpm</module>
<module>verification</module>
<module>abis_module</module>
</modules>
<groupId>ng.biosec</groupId>
<artifactId>integron</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<name>integron</name>
<description>Bio Connect Project</description>
<properties>
<java.version>1.8</java.version>
</properties>
<build>
<plugins>
<!-- tag::wsdl[] -->
<plugin>
<groupId>org.jvnet.jaxb2.maven2</groupId>
<artifactId>maven-jaxb2-plugin</artifactId>
<version>0.13.1</version>
<executions>
<execution>
<goals>
<goal>generate</goal>
</goals>
</execution>
</executions>
<configuration>
<schemaLanguage>WSDL</schemaLanguage>
<generatePackage>integron.client</generatePackage>
<schemas>
<schema>
<url>********?wsdl</url>
</schema>
</schemas>
</configuration>
</plugin>
<!-- end::wsdl[] -->
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</project>
The cpm module descriptor should be as follows:
<?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>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.1.RELEASE</version>
<relativePath/> <!-- lookup parent from integron.repository -->
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>cpm</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>ng.biosec</groupId>
<artifactId>enrollment_ws</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>ng.biosec</groupId>
<artifactId>abis_module</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.springframework.ws</groupId>
<artifactId>spring-ws-core</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</project>
Concerning the wsdl generated files, I guess they are getting generated but not packaged as the parent module packaging is set to be as pom.

Creating multi module project using Intellij & Maven

I have a project structure which has a core tool and a REST API to interact and configure that tool.
I have a package structure like this:
com.example.api -> contains API definitions
com.example.commons -> contains module common to both core and api
com.exmaple.core -> contains the core module
This is primarily a Spring Boot application and both will run in different containers. So the API and the Core jar will be different.
How do I create a multi-module project with this structure so that I can also use the commons module in both the sub packages(core & api).
Suggestions on how to configure Maven and IntelliJ in such an environment?
Is my pattern right? Are there other well known patterns for this kind of project structure?

You can have a multi Maven module project as you wish. Here's an example on how you should configure your modules:
Create a parent pom.xml as follows (note that I am not adding spring-boot-starter-parent as a parent to the project, I am bringing in the Spring Boot dependencies with spring-boot-dependencies):
<?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>com.example</groupId>
<artifactId>parent</artifactId>
<packaging>pom</packaging>
<version>1.0.0-SNAPSHOT</version>
<modules>
<module>example-commons</module>
<module>example-core</module>
<module>example-api</module>
</modules>
<dependencyManagement>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-dependencies -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>1.5.3.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-web -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>1.5.3.RELEASE</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-test -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<version>1.5.3.RELEASE</version>
</dependency>
</dependencies>
</project>
And a non executable module's pom.xml would be like:
<?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>
<artifactId>parent</artifactId>
<groupId>com.example</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>example-commons</artifactId>
</project>
whereas an executable module's pom.xml would be like (note the spring-boot-maven-plugin is present only here for this dependency):
<?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>
<artifactId>parent</artifactId>
<groupId>com.example</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>example-core</artifactId>
<build>
<plugins>
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-maven-plugin -->
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>1.5.3.RELEASE</version>
<configuration>
<executable>true</executable>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>com.example</groupId>
<artifactId>example-commons</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
</dependencies>
</project>

How to package a maven multi-module properly?

I'm building a multi-module rest service with Maven and Spring Boot that will be published on a WebLogic Server, and I'm a bit confuse about how to configure the packaging of the application modules.
My current structure is:
/application
/main (main mehtod for spring-boot)
/api
/service
/dao
The parent project (application folder) is set up as pom packaging, but child projects I'm not sure how to configure it. I believe the correct way would be packaging like .jar file, but i saw some examples on the internet of Java projects with Maven multi-modules defined as war.
can someone tell me what's the correct way to define the child modules packaging in this case?
My parent pom:
<?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>com.radarveicular</groupId>
<artifactId>radarveicular-application</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
<javax.inject.version>1</javax.inject.version>
</properties>
<modules>
<module>radarveicular-api</module>
<module>radarveicular-service</module>
<module>radarveicular-main</module>
<module>radarveicular-dao</module>
</modules>
<build>
<plugins>
<plugin>
<artifactId>maven-eclipse-plugin</artifactId>
<configuration>
<downloadSources>true</downloadSources>
<downloadJavadocs>true</downloadJavadocs>
<wtpversion>2.0</wtpversion>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
<encoding>${project.build.sourceEncoding}</encoding>
</configuration>
</plugin>
</plugins>
</build>
</project>
main pom:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-application</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>radarveicular-main</artifactId>
<dependencies>
<dependency>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-api</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<!-- Spring Framework -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-undertow</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
</dependency>
</dependencies>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
api pom:
<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>com.radarveicular</groupId>
<artifactId>radarveicular-application</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>radarveicular-api</artifactId>
<dependencies>
<dependency>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-service</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
</project>
service pom:
<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>com.radarveicular</groupId>
<artifactId>radarveicular-application</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>radarveicular-service</artifactId>
<dependencies>
<dependency>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-dao</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.3.7.RELEASE</version>
</dependency>
</dependencies>
</project>
dao pom:
<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>com.radarveicular</groupId>
<artifactId>radarveicular-application</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>radarveicular-dao</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.3.7.RELEASE</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.30</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.4</version>
</dependency>
</dependencies>
</project>

I think your problem is that your parent pom.xml shouldn't handle your spring boot project. Meaning, you should have this in it :
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
I recommend that your pom.xml parent only handles your modules and dependencies as pom packaging :
Packaging
<packaging>pom</packaging>
Modules
<modules>
<module>radarveicular-api</module>
<module>radarveicular-service</module>
<module>radarveicular-main</module>
<module>radarveicular-dao</module>
</modules>
Then, you will have your module radarveicular-main with the spring boot parent :
Parent
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
Packaging
<packaging>war</packaging>
I hope this will help you. =)

I feel your question is more towards designing part of multi module.
Multi module management of application can depend on various things.
One thing could be if you want to deploy each sub module as separate module/service based, which can be turned off/on based on need. In that case it would help you if you build each of module as separate war and deploy them separately.
If you have to deploy it as a single war than most straight forward would to create all dependent modules as jar and include them in parent project. In this way a single war will be deployed.
You can have a hybrid approach of above two.
Hopefully i have understood your question correctly. :)
Happy coding!!