Finish most codes and fix compile issue.

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;
     }

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;

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;