What does `kind="con"` mean in java gradle build files?

Question

I'm trying to understand this .classpath file in my java project that builds with gradle, but I'm confused what kind="con" means on the lines 16 and 17 <classpathentry /> elements...

.classpath

<?xml version="1.0" encoding="UTF-8"?>
<classpath>
    <classpathentry kind="src" output="bin/main"  path="src/main/java">
        <attributes>
            <attribute name="gradle_scope" value="main"/>
            <attribute name="gradle_used_by_scope" value="main,test"/>
        <attributes/>
    </classpathentry>
    <classpathentry kind="src" output="bin/test"  path="src/test/java">
        <attributes>
            <attribute name="gradle_scope" value="test"/>
            <attribute name="gradle_used_by_scope" value="test"/>
            <attribute name="test" value="true"/>
        <attributes/>
    </classpathentry>
    <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-21/">
    <classpathentry kind="con" path="org.eclipse.buildship.core.gradleclasspathcontainer">
</classpath>