Source attachment of Maven artefacts added by Tycho plug-in

Question

I'm using Maven Tycho to build my Eclipse IDE plug-in. This works very well, and Tycho adds tons of jar files to my local .m2.

Some of those have source attachments, but many don't. See the following screenshot:

How can I get Tycho to fetch the source for all artefacts?

The build section of my pom.xml looks like this:

    <build>
        <plugins>
            <plugin>
                <groupId>org.eclipse.tycho</groupId>
                <artifactId>tycho-maven-plugin</artifactId>
                <version>${tycho.version}</version>
                <extensions>true</extensions>
            </plugin>
            <plugin>
                <groupId>org.eclipse.tycho</groupId>
                <artifactId>tycho-compiler-plugin</artifactId>
                <version>${tycho.version}</version>
                <configuration>
                    <useProjectSettings>false</useProjectSettings>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.eclipse.tycho</groupId>
                <artifactId>tycho-p2-repository-plugin</artifactId>
                <version>${tycho.version}</version>
                <configuration>
                    <includeAllDependencies>false</includeAllDependencies>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.eclipse.tycho</groupId>
                <artifactId>tycho-packaging-plugin</artifactId>
                <version>${tycho.version}</version>
                <configuration>
                    <finalName>${project.artifactId}_${unqualifiedVersion}.${buildQualifier}</finalName>
                    <format>'v'yyyyMMddHHmm</format>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.eclipse.tycho</groupId>
                <artifactId>target-platform-configuration</artifactId>
                <version>${tycho.version}</version>
                <configuration>
                    <pomDependencies>consider</pomDependencies>
                    <environments>
                        <environment>
                            <os>linux</os> 
                            <ws>gtk</ws> 
                            <arch>x86_64</arch>
                        </environment>
                        <environment>
                            <os>win32</os> 
                            <ws>win32</ws> 
                            <arch>x86_64</arch>
                        </environment>
                        <environment>
                            <os>macosx</os> 
                            <ws>cocoa</ws> 
                            <arch>x86_64</arch>
                        </environment>
                    </environments>
                    <target>
                        <artifact>
                            <groupId>org.glassfish.eclipse</groupId>
                            <artifactId>org.glassfish.eclipse.${eclipse.target}</artifactId>
                            <version>${project.version}</version>
                        </artifact>
                    </target>
                </configuration>
            </plugin>
        </plugins>
    </build>