Why can’t Maven Tycho find the correct JDK in toolchains.xml?

I have made a simple RCP application to test Maven builds.

My question is why Maven Tycho can’t find the JDK’s defined in the toolchain and how can I fix those issues?

My RCP plugin uses JDK-15 and I believe that the target-platform brings the dependencies to JDK-11 and JDK-16.

I run ‘mvn clean verify’ and everything seems ok except of following two warnings:

[INFO] --- tycho-p2-publisher-plugin:2.3.0:publish-osgi-ee (default-publish-osgi-ee) @ info.wallberg.my_system.my_product ---
[WARNING] No system packages found in profile nor toolchain for JavaSE-11, using current JRE system packages.
This can cause faulty dependency resolution, consider adding a definition for a 'jdk' with id=JavaSE-11 in your toolchains.xml
[INFO] Published profile IUs: [config.a.jre.javase 11.0.0, a.jre.javase 11.0.0]
[INFO] Published profile IUs: [config.a.jre.javase 15.0.0, a.jre.javase 15.0.0]
[WARNING] No system packages found in profile nor toolchain for JavaSE-16, using current JRE system packages.
This can cause faulty dependency resolution, consider adding a definition for a 'jdk' with id=JavaSE-16 in your toolchains.xml
[INFO] Published profile IUs: [config.a.jre.javase 16.0.0, a.jre.javase 16.0.0]

My pom.xml looks like:

<project>
    <modelVersion>4.0.0</modelVersion>
    <groupId>info.wallberg.my_system</groupId>
    <artifactId>info.wallberg.my_system.root</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>pom</packaging>
    <properties>
        <tycho.version>2.3.0</tycho.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <!-- Skip the deployment here, submodules can override this property -->
        <!--maven.deploy.skip>true</maven.deploy.skip -->
    </properties>


    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.eclipse.tycho</groupId>
                    <artifactId>tycho-p2-director-plugin</artifactId>
                    <version>${tycho.version}</version>
                </plugin>
            </plugins>
        </pluginManagement>
        <plugins>
            <!--Enable the replacement of the SNAPSHOT version based on the last commit -->
            <!--<plugin> <groupId>org.eclipse.tycho</groupId> <artifactId>tycho-packaging-plugin</artifactId> 
                <version>${tycho.version}</version> <dependencies> <dependency> <groupId>org.eclipse.tycho.extras</groupId> 
                <artifactId>tycho-buildtimestamp-jgit</artifactId> <version>${tycho.version}</version> 
                </dependency> </dependencies> <configuration> <timestampProvider>jgit</timestampProvider> 
                <jgit.ignore>pom.xml</jgit.ignore> <jgit.dirtyWorkingTree>ignore</jgit.dirtyWorkingTree> 
                </configuration> </plugin> -->
            <!-- Skip the install, since we do not need the artifacts in our local 
                mvn repo -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-install-plugin</artifactId>
                <version>2.5.2</version>
                <configuration>
                    <skip>true</skip>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.eclipse.tycho</groupId>
                <artifactId>tycho-maven-plugin</artifactId>
                <version>${tycho.version}</version>
                <extensions>true</extensions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-toolchains-plugin</artifactId>
                <version>3.0.0</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>toolchain</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <toolchains>
                        <jdk>
                            <version>11</version>
                            <vendor>oracle</vendor>
                        </jdk>
                        <jdk>
                            <version>15</version>
                            <vendor>oracle</vendor>
                        </jdk>
                        <jdk>
                            <version>16.0.2</version>
                            <vendor>oracle</vendor>
                        </jdk>
                    </toolchains>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.eclipse.tycho</groupId>
                <artifactId>target-platform-configuration</artifactId>
                <version>${tycho.version}</version>
                <configuration>
                    <executionEnvironment>JavaSE-15</executionEnvironment>
                    <target>
                        <artifact>
                            <groupId>info.wallberg.my_system</groupId>
                            <artifactId>target-platform</artifactId>
                            <version>0.0.1-SNAPSHOT</version>
                        </artifact>
                    </target>
                    <environments>
                        <environment>
                            <os>linux</os>
                            <ws>gtk</ws>
                            <arch>x86_64</arch>
                        </environment>
                        <environment>
                            <os>win32</os>
                            <ws>win32</ws>
                            <arch>x86_64</arch>
                        </environment>
                        <environment>
                            <os>macosx</os>
                            <ws>cocoa</ws>
                            <arch>x86_64</arch>
                        </environment>
                    </environments>
                </configuration>
            </plugin>
            <!-- enable source feature generation -->
            <!--plugin> <groupId>org.eclipse.tycho.extras</groupId> <artifactId>tycho-source-feature-plugin</artifactId> 
                <version>${tycho.version}</version> <executions> <execution> <id>source-feature</id> 
                <phase>package</phase> <goals> <goal>source-feature</goal> </goals> </execution> 
                </executions> </plugin> <plugin> <groupId>org.eclipse.tycho</groupId> <artifactId>tycho-source-plugin</artifactId> 
                <version>${tycho.version}</version> <executions> <execution> <id>plugin-source</id> 
                <goals> <goal>plugin-source</goal> </goals> </execution> </executions> </plugin 
                <plugin> <groupId>com.github.spotbugs</groupId> <artifactId>spotbugs-maven-plugin</artifactId> 
                <version>3.1.3</version> <configuration> <effort>Max</effort> <threshold>Low</threshold> 
                <failOnError>false</failOnError> </configuration> </plugin> -->
        </plugins>
    </build>
    <modules>
        <module>bundles</module>
        <module>features</module>
        <module>releng</module>
        <module>tests</module>
    </modules>
</project>

My toolchains.xml looks like:

<?xml version="1.0" encoding="UTF-8"?>
<toolchains>
  <!-- JDK toolchains -->
  <toolchain>
    <type>jdk</type>
    <provides>
      <version>11</version>
      <vendor>oracle</vendor>
    </provides>
    <configuration>
      <jdkHome>C:Program FilesJavajdk-11</jdkHome>
    </configuration>
  </toolchain>
  <toolchain>
    <type>jdk</type>
    <provides>
      <version>15</version>
      <vendor>oracle</vendor>
    </provides>
    <configuration>
      <jdkHome>C:Program FilesJavajdk-15</jdkHome>
    </configuration>
  </toolchain>
  <toolchain>
    <type>jdk</type>
    <provides>
      <version>16.0.2</version>
      <vendor>oracle</vendor>
    </provides>
    <configuration>
      <jdkHome>C:Program FilesJavajdk-16.0.2</jdkHome>
    </configuration>
  </toolchain>
</toolchains>

Answer

Tycho looks for the Execution Environment in an <id> section in the <provides> list.

For example, I have:

<toolchain>
   <type>jdk</type>
   <provides>
       <id>JavaSE-16</id>
   </provides>
   <configuration>
      <jdkHome>/Library/Java/JavaVirtualMachines/jdk-16.0.2.jdk/Contents/Home</jdkHome>
   </configuration>
</toolchain>

For JavaSE-16