Maven 4: A Modernized Java Build System

Model Version 4.1.0

Maven 4 updates the POM version to 4.1.0, offering compatibility with version 4.0.0 while adding new elements and deprecating others. While updating existing projects is optional, new features require the updated POM version for full functionality.

Maven 3’s monolithic POMs often included build metadata, bloating dependency resolution and exposing internal details. Maven 4 addresses this by separating the Build POM from the Consumer POM, streamlining dependency management and enhancing project clarity.

Key Insights

• Maven 3 appeared in 2010, marking a long wait for a major update.
• Build/Consumer separation (“flattening”) reduces dependency resolution overhead.
• New artifact types like classpath-jar and module-jar provide explicit control over classpath behavior.

Working Example

<project
xmlns="http://maven.apache.org/POM/4.1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.1.0 http://maven.apache.org/xsd/maven-4.1.0.xsd">
<modelVersion>4.1.0</modelVersion>
<!-- ... -->
</project>

<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<type>classpath-processor</type>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>

Practical Applications

• Large Enterprises: Streamlining dependency management across hundreds of projects with the build/consumer separation.
• Pitfall: Failing to update plugins to versions compatible with Maven 4, leading to build errors.

References:

• https://www.baeldung.com/maven-4-upgrades