feat: linux control group version 2 API support cgroup v2

src/integrationtests/java/com/aws/greengrass/integrationtests/lifecyclemanager/GenericExternalServiceIntegTest.java

@@ -41,6 +41,7 @@
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
+import org.mockito.Spy;
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import java.io.IOException;
@@ -95,6 +96,7 @@
 class GenericExternalServiceIntegTest extends BaseITCase {
     private Kernel kernel;
 
+    @Spy
     LinuxPlatform linuxPlatform;
 
     private final static String ROOT_PATH_STRING = "/systest21/fs/cgroup";
@@ -655,10 +657,13 @@ void GIVEN_linux_resource_limits_WHEN_it_changes_THEN_component_runs_with_new_re
             }
         });
 
-        linuxPlatform = kernel.getContext().get(LinuxPlatform.class);
+        linuxPlatform = spy(kernel.getContext().get(LinuxPlatform.class));
 
         createComponentData(echoComponentName);
         createComponentData(mainComponentName);
+
+        // Due to cgroup v1 is active by default (in test platform), and the directories of cgroup v1 are read-only
+        // therefore, here create some directories and files as fake cgroup v2 files to support testing
         Field controllerField = LinuxPlatform.class.getDeclaredField("CGROUP_CONTROLLERS");
         setFinalStatic(controllerField, Paths.get(componentPathString + "/memory.max"));
         systemResourceController = linuxPlatform.getSystemResourceController();