.github/workflows/.toolchains.xml

<?xml version="1.0" encoding="UTF8"?>
<toolchains>
    <toolchain>
        <type>jdk</type>
        <provides>
            <version>1.8</version>
            <vendor>openjdk</vendor>
        </provides>
        <configuration>
            <jdkHome>${env.JAVA8_HOME}</jdkHome>
        </configuration>
    </toolchain>
    <toolchain>
        <type>jdk</type>
        <provides>
            <version>8</version>
            <vendor>openjdk</vendor>
        </provides>
        <configuration>
            <jdkHome>${env.JAVA8_HOME}</jdkHome>
        </configuration>
    </toolchain>
    <toolchain>
        <type>jdk</type>
        <provides>
            <version>11</version>
            <vendor>openjdk</vendor>
        </provides>
        <configuration>
            <jdkHome>${env.JAVA11_HOME}</jdkHome>
        </configuration>
    </toolchain>
    <toolchain>
        <type>jdk</type>
        <provides>
            <version>12</version>
            <vendor>openjdk</vendor>
        </provides>
        <configuration>
            <jdkHome>${env.JAVA12_HOME}</jdkHome>
        </configuration>
    </toolchain>
    <toolchain>
        <type>jdk</type>
        <provides>
            <version>13</version>
            <vendor>openjdk</vendor>
        </provides>
        <configuration>
            <jdkHome>${env.JAVA13_HOME}</jdkHome>
        </configuration>
    </toolchain>
</toolchains>