sonar-maven-plugin fails to recognise jdk version from "maven.compiler.release"

Behaviour of sonar-maven-plugin varies when maven-compiler-plugin is/isn't defined. I spent some time to find out the proper setting.

Create a simple Java maven project and keep the pom.xml simple.

<?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.example</groupId>
    <artifactId>testing</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.release>17</maven.compiler.release>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

</project>

Execution

mvn org.sonarsource.scanner.maven:sonar-maven-plugin:<version>:sonar -Dsonar.login=<token>

Case 1:

• sonarqube-maven-plugin version: 3.7.0.1746

• pom.xml with maven.compiler.release defined.

• maven-compiler-plugin is NOT defined in pom.xml

Result:

Configured Java source version (sonar.java.source): 5

Case 2:

• sonarqube-maven-plugin version: 3.7.0.1746

• pom.xml with maven.compiler.release defined

• pom.xml with maven.compiler.source defined

• maven-compiler-plugin is NOT defined in pom.xml

Result:

(It means the plugin can only get the version from source instead of release)

Configured Java source version (sonar.java.source): 17

Case 3:

• sonarqube-maven-plugin version: 3.7.0.1746

• pom.xml with maven.compiler.release defined

• maven-compiler-plugin (3.8.1) is defined

Result:

(No idea why the version changes when maven compiler plugin is defined.)

Configured Java source version (sonar.java.source): 6

Case 4:

• sonarqube-maven-plugin version: 3.7.0.1746

• pom.xml with maven.compiler.release defined

• maven-compiler-plugin (3.10.1) is defined

Result:

(No idea why the version changes when different version of maven compiler plugin is defined.)

Configured Java source version (sonar.java.source): 7

Case 5:

• sonarqube-maven-plugin version: 3.9.1.2184

• pom.xml with maven.compiler.release defined

• maven-compiler-plugin is NOT defined in pom.xml

Result:

(Upgrading sonar maven plugin doesn't help.)

Configured Java source version (sonar.java.source): 5

Proper setting

• sonarqube-maven-plugin with version 3.8.0 or above.

• Define maven-compiler-plugin in pom.xml with version 3.6.0 or above.

Execution:

mvn org.sonarsource.scanner.maven:sonar-maven-plugin:3.9.1.2184:sonar -Dsonar.login=<token>

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>org.example</groupId>
    <artifactId>testing</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.release>17</maven.compiler.release>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.10.1</version>
            </plugin>
        </plugins>
    </build>

</project>