无法执行目标org.apache.maven.plugins：maven-jar-plugin：2.4：jar

Question

So I was trying to go ahead and create a .ear file for an existing maven project and further deploy it on WebLogic server . For the same, I went ahead to create the WAR , JAR and the EAR module and followed these steps for it -

Right click on parent project , select new , select maven module , Named it as projectnameJARModule and then finished the wizard .

Did the same process for creating a projectnameWARModule and a projectnameEARModule module. Once they were made, I added the WAR and the JAR modules as dependencies to the EAR module .Further, I went ahead to install the maven modules by Right Clicking on the projectnameWARModule folder and chose Run As - Maven Install . Upon this, I get the following error in the console (Full console log below) -

---

T E S T S
-------------------------------------------------------
Running org.CADJARModule.AppTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

[INFO] 
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ CADJARModule ---
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO] 
[INFO] projectname ............................................... SUCCESS [  0.957 s]
[INFO] projectnameJARModule ...................................... FAILURE [ 33.425 s]
[INFO] projectnameWARModule Maven Webapp ......................... SKIPPED
[INFO] projectnameEARModule ...................................... SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 34.806 s
[INFO] Finished at: 2015-12-01T18:16:20+05:30
[INFO] Final Memory: 9M/126M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-jar-plugin:2.4:jar (default-jar) on project projectnameJARModule: Error assembling JAR: For artifact {org.glassfish.jersey.containers:jersey-container-servlet-core:null:jar}: The version cannot be empty. -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
[ERROR] 
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR]   mvn <goals> -rf :projectnameJARModule

Any idea how do I get rid of this? Many Thanks

Following is the pom.xml for the Parent Module -

<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>Project_name</groupId>
<artifactId>Project_name</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<name>Project_name</name>
<build>
    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
                <version>2.5.1</version>
                <inherited>true</inherited>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
    <plugin>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.4</version>
        <configuration>
        <warSourceDirectory>WebContent</warSourceDirectory>
        <failOnMissingWebXml>false</failOnMissingWebXml>
        </configuration>
    </plugin>
    </plugins>
</build>
<dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.glassfish.jersey</groupId>
                <artifactId>jersey-bom</artifactId>
                <version>${jersey.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.fasterxml.jackson.jaxrs</groupId>
                <artifactId>jackson-jaxrs-json-provider</artifactId>
                <version>2.6.0</version>
        </dependency>
        <dependency>
                    <groupId>javax</groupId>
                    <artifactId>javaee-web-api</artifactId>
                    <version>7.0</version> <!-- Put here the version of your Java EE app, in my case 7.0 -->
                    <scope>provided</scope>
            </dependency>

          <dependency>
                    <groupId>javax.servlet</groupId>
                    <artifactId>javax.servlet-api</artifactId>
                    <version>3.1.0</version>
                    <scope>provided</scope>
            </dependency>

            <dependency>
                    <groupId>javax.servlet</groupId>
                    <artifactId>jstl</artifactId>
                    <version>1.2</version>
            </dependency>

        <dependency>
            <groupId>org.glassfish.jersey.containers</groupId>
            <artifactId>jersey-container-servlet-core</artifactId>
            <!-- use the following artifactId if you don't need servlet 2.x compatibility -->
            <!-- artifactId>jersey-container-servlet</artifactId -->
        </dependency>

        <dependency>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-moxy</artifactId>
        </dependency>
        </dependencies>
    </dependencyManagement>


    <properties>
        <jersey.version>2.16</jersey.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <modules>
        <module>Project_nameJARModule</module>
        <module>Project_nameWARModule</module>
        <module>Project_nameEARModule</module>
    </modules>
</project>

Following is the pom.xml for the WAR Module -

    <?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
    <groupId>Projectname</groupId>
    <artifactId>Projectname</artifactId>
    <version>0.0.1-SNAPSHOT</version>
</parent>
<groupId>ProjectnameWARModule</groupId>
<artifactId>ProjectnameWARModule</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<name>ProjectnameWARModule Maven Webapp</name>
<url>http://maven.apache.org</url>
<dependencies>
    <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>3.8.1</version>
    <scope>test</scope>
    </dependency>
</dependencies>
<build>
    <finalName>ProjectnameWARModule</finalName>
</build>
</project>

Following is the pom.xml for my JAR module -

    <?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
    <groupId>Project_Name</groupId>
    <artifactId>Project_Name</artifactId>
    <version>0.0.1-SNAPSHOT</version>
</parent>
<groupId>CADJARModule</groupId>
<artifactId>CADJARModule</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>CADJARModule</name>
<url>http://maven.apache.org</url>
<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
    <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>3.8.1</version>
    <scope>test</scope>
    </dependency>
</dependencies>
</project>

Answer 1

Let me clarify: the dependencyManagement section provide dependencies governance to the same POM where it is defined and to children/modules Maven projects. However, declaring a dependency in the dependencyManagement section doesn't mean Maven will use it, it's just an hint in case Maven will use it so that if a certain version is missing in the dependencies section, Maven will look it up in the dependencyManagement section. If none is found then, an error will be generated (Maven couldn't know which version to resolve for a certain dependency).

Hence, good to have the dependencyManagement section for governance, but it should always define versions of each dependency, otherwise it would be a missed opportunity and make your build more error-prone.

If you need all of the declared dependencies and only in the scope of the same declaring POM, then you can actually avoid to have a dependenciesManagement section at all and just have your dependencies section providing versions for each declared dependency.

In this case, you are using a dependenciesManagement section in your parent POM (I see it has modules), you should then check if in the jar module the same dependency is declared (if required), otherwise it will not be used during its build. Moreover, you should also check whether another dependenciesManagement section is declared in the concerned module and re-declaring the same dependency again without version.

Some additional helps can be provided by:

• Running your Maven build using the -e -X flags
• Running mvn dependency:tree -Dincludes=<concerned_group_id_here>
• Last change option, run your build as mvn dependency:purge-local-repository clean install , which can work in case of corrupted cache (error should be different though)