Sonar coverage always 0 in multi module project

Question

I am developing a multi module maven project structured as follows:

Parent
   |----Client 
   |----Server
   |----End2End

Server is a spring boot application that yields a REST interface. Client is a simple swing application which uses that REST interface, and End2End is a module containing some end to end tests (client/server). Coming inside the real problem, this is my properties in parent pom:

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
    <jacoco.data.file>${project.build.directory}/jacoco.exec</jacoco.data.file>
    <jacoco.report.path>${project.reporting.outputDirectory}</jacoco.report.path>
    <sonar.language>java</sonar.language>
    <sonar.jacoco.reportPaths>${project.reporting.outputDirectory}</sonar.jacoco.reportPaths>
</properties>

And here it is my build section

 <build>
            <pluginManagement>
                <plugins>
                    <plugin>
                        <groupId>org.eluder.coveralls</groupId>
                        <artifactId>coveralls-maven-plugin</artifactId>
                        <version>4.3.0</version>
                        <configuration>
                            <jacocoReports>
                                <jacocoReport>${project.reporting.outputDirectory}/jacoco.xml</jacocoReport>
                            </jacocoReports>
                        </configuration>
                    </plugin>
                </plugins>
            </pluginManagement>

            <plugins>
                <plugin>
                    <groupId>org.jacoco</groupId>
                    <artifactId>jacoco-maven-plugin</artifactId>
                    <version>0.7.9</version>
                    <configuration>
                        <excludes>
                            <exclude>**/ServerApplication.*</exclude>
                            <exclude>**/DatabaseGrid.*</exclude>
                            <exclude>**/WebSecurityConfig.*</exclude>
                            <exclude>**/App.*</exclude>
                            <exclude>**/DatabaseGrid.*</exclude>
                            <exclude>**/GridFromServer.*</exclude>
                        </excludes>
                    </configuration>
                    <executions>
                        <execution>
                            <goals>
                                <!-- binds by default to the phase "initialize" -->
                                <goal>prepare-agent</goal>
                                <!-- binds by default to the phase "verify" -->
                                <goal>report</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
            </plugins>
 </build>

When I launch a build such as

mvn clean verify coveralls:report

My overall code coverage is correctly reported on coveralls. But when I launch:

mvn clean verify sonar:sonar

The analysis works but code coverage remain always at 0%. I am sure that I'm mistaking something with report paths, jacoco report is in parent/target/jacoco.exec. Can anyone help me?

Answer 1

<sonar.jacoco.reportPaths>${project.reporting.outputDirectory}</sonar.jacoco.reportPaths>

specifies directory, whereas according to SonarQube documentation should specify exec files.