diff --git a/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/ApplicationConfiguration.java b/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/ApplicationConfiguration.java
index 3e7c952aebf8184f7416dd55211554dde45183fa..5984f32a05e58b1a7a7edacdecf0fa21a1efd7b9 100644
--- a/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/ApplicationConfiguration.java
+++ b/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/ApplicationConfiguration.java
@@ -28,10 +28,19 @@ public class ApplicationConfiguration {
         return modules.keySet().toArray(new String[0]);
     }
 
+    public ModuleConfiguration addModule(String moduleName) {
+        ModuleConfiguration newModule = new ModuleConfiguration();
+        modules.put(moduleName, newModule);
+        return newModule;
+    }
+
     public ModuleConfiguration getModuleConfiguration(String name) {
         return modules.get(name);
     }
 
+    /**
+     * The configurations about a certain module.
+     */
     public class ModuleConfiguration {
         private HashMap<String, ProviderConfiguration> providers = new HashMap<>();
 
@@ -40,6 +49,9 @@ public class ApplicationConfiguration {
         }
     }
 
+    /**
+     * The configuration about a certain provider of a module.
+     */
     public class ProviderConfiguration {
         private Properties properties;
     }
diff --git a/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/Module.java b/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/Module.java
index cebc7b88345ad69c8da1495bdafe979a4ab3c531..fd0d18b5a8abec5960839d14732dbda1a5f1a322 100644
--- a/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/Module.java
+++ b/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/Module.java
@@ -18,7 +18,6 @@
 
 package org.skywalking.apm.collector.modulization;
 
-import java.lang.reflect.InvocationTargetException;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.ServiceLoader;
diff --git a/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/ModuleProvider.java b/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/ModuleProvider.java
index abd5fecd6452d31eda7d56a03176d28809efd0aa..74bc182654e47f4b3d7558abc59f66fa64022980 100644
--- a/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/ModuleProvider.java
+++ b/apm-collector/apm-collector-modulization-core/src/main/java/org/skywalking/apm/collector/modulization/ModuleProvider.java
@@ -76,6 +76,7 @@ public abstract class ModuleProvider {
 
     /**
      * Register a implementation for the service of this module provider.
+     *
      * @param serviceType
      * @param service
      */
@@ -83,6 +84,12 @@ public abstract class ModuleProvider {
         this.services.put(serviceType, service);
     }
 
+    /**
+     * Make sure all required services have been implemented.
+     *
+     * @param requiredServices must be implemented by the module.
+     * @throws ServiceNotProvidedException when exist unimplemented service.
+     */
     void requiredCheck(Class<? extends Service>[] requiredServices) throws ServiceNotProvidedException {
         if (requiredServices == null)
             return;