Question: I have a Spring Boot application and I have created a Jar out of that. Following is my `pom.xml`:

```
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-mail</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>
    <dependency>
        <groupId>org.thymeleaf.extras</groupId>
        <artifactId>thymeleaf-extras-java8time</artifactId>
        <version>2.1.0.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <!-- WebJars -->
    <dependency>
        <groupId>javax.mail</groupId>
        <artifactId>mail</artifactId>
        <version>1.4.7</version>
    </dependency>
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.6.2</version>
    </dependency>
</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

```

I want to use this Jar in my other application so added this jar to my application. But when I am calling a method in that Jar, it is throwing a `ClassNotFoundException`.

How can I fix this issue? How can I add a dependency to a Spring Boot JAR?

Answer: 
You can extend your project by maven-assembly-plugin

```
<plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>3.1.0</version>
        <configuration>
        <descriptorRefs>
                <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
        </configuration>
        <executions>
        <execution>
            <id>make-assembly</id>
            <phase>package</phase>
            <goals>
            <goal>single</goal>
            </goals>
            </execution>
        </executions>
</plugin>

```

After the build you will get 3 jars. The main one will be the same as a usual Maven project, while the second one will have the classifier appended with exec and be the executable JAR. The third jar name will be appended by jar-with-dependencies and will contain your classes with classes added as dependencies in your spring boot application(spring-boot-starter-web, thymeleaf,...), so into the pom of the application where you want to add that project as dependencie you won't have to add dependencies from spring boot project.
All existing answers are made under the assumption that the Spring Boot project upon which another project should depend is an application, which is fair enough since the question is phrased like that.

But if the underlying project is meant to be used as a library *only*, i.e. it contains no (sensible) Main class, there is obviously no executable code that needs to be repackaged at all.

So in that case, it makes more sense to skip the repackaging entirely like this:

```
<plugins>
    <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <executions>
            <execution>
                <id>repackage</id>
                <configuration>
                    **<skip>true</skip>**
                </configuration>
            </execution>
        </executions>
    </plugin>
</plugins>
```