Spring Boot plugin duplicates dependencies

Recently I found that Spring Boot Maven plugin duplicates some dependencies in the output war file. The problem with time-stamped snapshot dependencies (they have versions like "1.1-20170206.160055-1"). In this case Spring Boot plugin puts both "1.1-SNAPSHOT" and "1.1-20170206.160055-1" versions of jars. Like here:

demo-webapp-1.1-20170206.160055-1.war:\WEB-INF\lib\
                        demo-core-1.1-SNAPSHOT.jar 
                        demo-core-1.1-20170206.160055-1.jar 

This is not critical (application will work), but unpleasant.

The problem occurs with a Spring Boot Maven plugin version before 1.4.4. With 1.4.4 it works fine. So just switch plugin to the 1.4.4, even if you use are using an earlier version of Spring Boot.

<plugins>
    <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <version>1.4.4.RELEASE</version>
    </plugin>
...

After that it will keep only one file per dependency:

demo-webapp-1.1-20170206.160055-1.war:\WEB-INF\lib\
                        demo-core-1.1-SNAPSHOT.jar 

Get Spring Boot sources

Spring Boot sources

Very often it is helpful for me to look into the Spring sources in order to understand how some internals work. Of course it is pretty simple to automatically download and view sources using IDE (like IntelliJ IDEA). But sometimes I need just plain source files.
I get these files using "Maven Dependency Plugin" and this pom.xml 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>

    <groupId>io.github.xantorohara.springfield</groupId>
    <artifactId>spring-boot-sources</artifactId>
    <version>0.1</version>
    <packaging>pom</packaging>
    <name>spring-boot-sources</name>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.6.RELEASE</version>
        <relativePath/>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <!-- Spring Boot and Spring Framework libraries -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-cache</artifactId>
        </dependency>

        <!-- My current needs -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.2.0</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <version>3.0.0</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>unpack-dependencies</goal>
                        </goals>
                        <configuration>
                            <classifier>sources</classifier>
                            <outputDirectory>target</outputDirectory>
                            <includeGroupIds>
                                org.springframework,
                                org.springframework.boot,
                                org.mybatis,
                                org.mybatis.spring.boot
                            </includeGroupIds>
                            <useSubDirectoryPerArtifact>true</useSubDirectoryPerArtifact>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

Download source code into the target directory using this command:

mvn process-sources

Just add another dependencies if you need.