diff --git a/CHANGELOG.md b/CHANGELOG.md
index 03749ce..474d44e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@
     8. 修改类中使用集合字段未指定泛型可能出错的bug。
     9. 优化set等集合类在文档中的类型显示。
     10. 添加对集合字段中枚举的处理。
+    11. 枚举序列化支持优化。
 #### 版本号：2.0.1
 - 更新日期: 2020-12-20
 - 更新内容：
diff --git a/src/main/java/com/power/doc/helper/JsonBuildHelper.java b/src/main/java/com/power/doc/helper/JsonBuildHelper.java
index c1d2e70..60f6a5b 100644
--- a/src/main/java/com/power/doc/helper/JsonBuildHelper.java
+++ b/src/main/java/com/power/doc/helper/JsonBuildHelper.java
@@ -52,7 +52,7 @@ public class JsonBuildHelper {
     public static String buildReturnJson(DocJavaMethod docJavaMethod, ProjectDocConfigBuilder builder) {
         JavaMethod method = docJavaMethod.getJavaMethod();
         if (method.getReturns().isVoid()) {
-            return "void";
+            return "Doesn't return a value.";
         }
         String returnTypeGenericCanonicalName = method.getReturnType().getGenericCanonicalName();
         if (Objects.nonNull(builder.getApiConfig().getResponseBodyAdvice())
diff --git a/src/main/java/com/power/doc/helper/ParamsBuildHelper.java b/src/main/java/com/power/doc/helper/ParamsBuildHelper.java
index 8ebe27f..ed88eb9 100644
--- a/src/main/java/com/power/doc/helper/ParamsBuildHelper.java
+++ b/src/main/java/com/power/doc/helper/ParamsBuildHelper.java
@@ -343,12 +343,13 @@ public class ParamsBuildHelper {
                                 if (gName.length() == 1) {
                                     // handle generic
                                     int len = globGicName.length;
-                                    if (len > 0) {
-                                        String gicName = genericMap.get(gName) != null ? genericMap.get(gName) : globGicName[0];
-                                        if (!JavaClassValidateUtil.isPrimitive(gicName) && !simpleName.equals(gicName)) {
-                                            paramList.addAll(buildParams(gicName, preBuilder.toString(), nextLevel, isRequired,
-                                                    responseFieldMap, isResp, registryClasses, projectBuilder, groupClasses, fieldPid));
-                                        }
+                                    if (len < 1) {
+                                        continue out;
+                                    }
+                                    String gicName = genericMap.get(gName) != null ? genericMap.get(gName) : globGicName[0];
+                                    if (!JavaClassValidateUtil.isPrimitive(gicName) && !simpleName.equals(gicName)) {
+                                        paramList.addAll(buildParams(gicName, preBuilder.toString(), nextLevel, isRequired,
+                                                responseFieldMap, isResp, registryClasses, projectBuilder, groupClasses, fieldPid));
                                     }
                                 } else {
                                     paramList.addAll(buildParams(gName, preBuilder.toString(), nextLevel, isRequired,
@@ -412,7 +413,7 @@ public class ParamsBuildHelper {
                         }
                     }
                 }
-            }
+            }//end field
         }
         return paramList;
     }
@@ -454,7 +455,7 @@ public class ParamsBuildHelper {
         String enumComments = javaClass.getComment();
         if (projectBuilder.getApiConfig().getInlineEnum()) {
             ApiDataDictionary dataDictionary = projectBuilder.getApiConfig().getDataDictionary(javaClass.getSimpleName());
-            if (dataDictionary == null) {
+            if (Objects.isNull(dataDictionary)) {
                 comment = comment + "<br/>" + JavaClassUtil.getEnumParams(javaClass);
             } else {
                 comment = comment + "[enum:" + dictionaryListComment(dataDictionary) + "]";
@@ -462,7 +463,7 @@ public class ParamsBuildHelper {
         } else {
             enumComments = DocUtil.replaceNewLineToHtmlBr(enumComments);
             comment = comment + "<br/>" + JavaClassUtil.getEnumParams(javaClass) + "<br/>";
-            if (enumComments != null) {
+            if (StringUtil.isNotEmpty(enumComments)) {
                 comment = comment + "(See: " + enumComments + ")";
             }
             comment = StringUtil.removeQuotes(comment);
diff --git a/src/main/java/com/power/doc/template/IDocBuildTemplate.java b/src/main/java/com/power/doc/template/IDocBuildTemplate.java
index b14eba4..04e9050 100644
--- a/src/main/java/com/power/doc/template/IDocBuildTemplate.java
+++ b/src/main/java/com/power/doc/template/IDocBuildTemplate.java
@@ -95,7 +95,7 @@ public interface IDocBuildTemplate<T> {
     default List<ApiParam> buildReturnApiParams(DocJavaMethod docJavaMethod, ProjectDocConfigBuilder projectBuilder) {
         JavaMethod method = docJavaMethod.getJavaMethod();
         if (method.getReturns().isVoid()) {
-            return null;
+            return new ArrayList<>(0);
         }
         String returnTypeGenericCanonicalName = method.getReturnType().getGenericCanonicalName();
         if (Objects.nonNull(projectBuilder.getApiConfig().getResponseBodyAdvice())
@@ -117,33 +117,33 @@ public interface IDocBuildTemplate<T> {
 
         String typeName = apiReturn.getSimpleName();
         if (this.ignoreReturnObject(typeName, projectBuilder.getApiConfig().getIgnoreRequestParams())) {
-            return null;
+            return new ArrayList<>(0);
         }
         if (JavaClassValidateUtil.isPrimitive(typeName)) {
             docJavaMethod.setReturnSchema(OpenApiSchemaUtil.primaryTypeSchema(typeName));
-            return null;
+            return new ArrayList<>(0);
         }
         if (JavaClassValidateUtil.isCollection(typeName)) {
             if (returnType.contains("<")) {
                 String gicName = returnType.substring(returnType.indexOf("<") + 1, returnType.lastIndexOf(">"));
                 if (JavaClassValidateUtil.isPrimitive(gicName)) {
                     docJavaMethod.setReturnSchema(OpenApiSchemaUtil.arrayTypeSchema(gicName));
-                    return null;
+                    return new ArrayList<>(0);
                 }
                 return ParamsBuildHelper.buildParams(gicName, "", 0, null, projectBuilder.getCustomRespFieldMap(),
                         Boolean.TRUE, new HashMap<>(), projectBuilder, null, 0);
             } else {
-                return null;
+                return new ArrayList<>(0);
             }
         }
         if (JavaClassValidateUtil.isMap(typeName)) {
             String[] keyValue = DocClassUtil.getMapKeyValueType(returnType);
             if (keyValue.length == 0) {
-                return null;
+                return new ArrayList<>(0);
             }
             if (JavaClassValidateUtil.isPrimitive(keyValue[1])) {
                 docJavaMethod.setReturnSchema(OpenApiSchemaUtil.mapTypeSchema(keyValue[1]));
-                return null;
+                return new ArrayList<>(0);
             }
             return ParamsBuildHelper.buildParams(keyValue[1], "", 0, null, projectBuilder.getCustomRespFieldMap(),
                     Boolean.TRUE, new HashMap<>(), projectBuilder, null, 0);
@@ -152,7 +152,7 @@ public interface IDocBuildTemplate<T> {
             return ParamsBuildHelper.buildParams(returnType, "", 0, null, projectBuilder.getCustomRespFieldMap(),
                     Boolean.TRUE, new HashMap<>(), projectBuilder, null, 0);
         }
-        return null;
+        return new ArrayList<>(0);
     }
 
     List<T> getApiData(ProjectDocConfigBuilder projectBuilder);
diff --git a/src/main/java/com/power/doc/utils/ApiParamTreeUtil.java b/src/main/java/com/power/doc/utils/ApiParamTreeUtil.java
index 624cb5e..3f60251 100644
--- a/src/main/java/com/power/doc/utils/ApiParamTreeUtil.java
+++ b/src/main/java/com/power/doc/utils/ApiParamTreeUtil.java
@@ -35,12 +35,12 @@ public class ApiParamTreeUtil {
 
     public static List<ApiParam> apiParamToTree(List<ApiParam> apiParamList) {
         if (Objects.isNull(apiParamList)) {
-            return null;
+            return new ArrayList<>(0);
         }
         List<ApiParam> params = new ArrayList<>();
         // find root
         for (ApiParam apiParam : apiParamList) {
-            //去除filed的前缀
+            // remove pre of field
             apiParam.setField(apiParam.getField().replaceAll("└─", "").replaceAll("&nbsp;", ""));
             // pid == 0
             if (apiParam.getPid() == 0) {
@@ -48,7 +48,7 @@ public class ApiParamTreeUtil {
             }
         }
         for (ApiParam apiParam : params) {
-            //去除filed的前缀
+            // remove pre of field
             apiParam.setChildren(getChild(apiParam.getId(), apiParamList));
         }
         return params;
@@ -72,7 +72,7 @@ public class ApiParamTreeUtil {
             param.setChildren(getChild(param.getId(), apiParamList));
         }
         if (childList.size() == 0) {
-            return null;
+            return new ArrayList<>(0);
         }
         return childList;
     }
diff --git a/src/main/java/com/power/doc/utils/BeetlTemplateUtil.java b/src/main/java/com/power/doc/utils/BeetlTemplateUtil.java
index b104c2f..c9d0eae 100644
--- a/src/main/java/com/power/doc/utils/BeetlTemplateUtil.java
+++ b/src/main/java/com/power/doc/utils/BeetlTemplateUtil.java
@@ -32,6 +32,7 @@ import java.io.File;
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 
 /**
  * Beetl template handle util
@@ -75,7 +76,7 @@ public class BeetlTemplateUtil {
             if (f.isFile()) {
                 String fileName = f.getName();
                 Template tp = gt.getTemplate(fileName);
-                if (null != params) {
+                if (Objects.nonNull(params)) {
                     tp.binding(params);
                 }
                 templateMap.put(fileName, tp.render());
@@ -95,7 +96,7 @@ public class BeetlTemplateUtil {
             GroupTemplate gt = new GroupTemplate(resourceLoader, cfg);
             return gt;
         } catch (IOException e) {
-            throw new RuntimeException("Can't get Beetl template.");
+            throw new RuntimeException("Can't found Beetl template.");
         }
     }
 }
diff --git a/src/main/java/com/power/doc/utils/CurlUtil.java b/src/main/java/com/power/doc/utils/CurlUtil.java
index 44e928c..b852be0 100644
--- a/src/main/java/com/power/doc/utils/CurlUtil.java
+++ b/src/main/java/com/power/doc/utils/CurlUtil.java
@@ -1,3 +1,25 @@
+/*
+ * smart-doc
+ *
+ * Copyright (C) 2018-2021 smart-doc
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
 package com.power.doc.utils;
 
 import com.power.common.util.CollectionUtil;
diff --git a/src/main/java/com/power/doc/utils/Iterables.java b/src/main/java/com/power/doc/utils/Iterables.java
index b78b625..fc572f7 100644
--- a/src/main/java/com/power/doc/utils/Iterables.java
+++ b/src/main/java/com/power/doc/utils/Iterables.java
@@ -21,6 +21,9 @@
  * under the License.
  */
 
+/**
+ * @author daiww 2020/08/26.
+ */
 package com.power.doc.utils;
 
 import java.util.function.BiConsumer;
@@ -28,7 +31,7 @@ import java.util.function.BiConsumer;
 public class Iterables {
     public static <E> void forEach(
             Iterable<? extends E> elements, BiConsumer<Integer, ? super E> action) {
-        if(elements==null||action==null) return;
+        if (elements == null || action == null) return;
         int index = 0;
         for (E element : elements) {
             action.accept(index++, element);
diff --git a/src/main/java/com/power/doc/utils/JavaClassUtil.java b/src/main/java/com/power/doc/utils/JavaClassUtil.java
index 8572b58..3a5005f 100644
--- a/src/main/java/com/power/doc/utils/JavaClassUtil.java
+++ b/src/main/java/com/power/doc/utils/JavaClassUtil.java
@@ -57,12 +57,12 @@ public class JavaClassUtil {
      */
     public static List<DocJavaField> getFields(JavaClass cls1, int counter, Set<String> addedFields) {
         List<DocJavaField> fieldList = new ArrayList<>();
-        if (null == cls1) {
+        if (Objects.isNull(cls1)) {
             return fieldList;
         } else if ("Object".equals(cls1.getSimpleName()) || "Timestamp".equals(cls1.getSimpleName()) ||
                 "Date".equals(cls1.getSimpleName()) || "Locale".equals(cls1.getSimpleName())
                 || "ClassLoader".equals(cls1.getSimpleName()) || JavaClassValidateUtil.isMap(cls1.getFullyQualifiedName())
-                || cls1.isEnum()) {
+                || cls1.isEnum() || "Serializable".equals(cls1.getSimpleName())) {
             return fieldList;
         } else {
             String className = cls1.getFullyQualifiedName();
@@ -285,7 +285,7 @@ public class JavaClassUtil {
      * @return JavaClass
      */
     public static List<JavaType> getActualTypes(JavaType javaType) {
-        if (null == javaType) {
+        if (Objects.isNull(javaType)) {
             return new ArrayList<>(0);
         }
         String typeName = javaType.getGenericFullyQualifiedName();
@@ -454,7 +454,7 @@ public class JavaClassUtil {
     }
 
     public static void genericParamMap(Map<String, String> genericMap, JavaClass cls, String[] globGicName) {
-        if (cls != null && null != cls.getTypeParameters()) {
+        if (Objects.nonNull(cls) && Objects.nonNull(cls.getTypeParameters())) {
             List<JavaTypeVariable<JavaGenericDeclaration>> variables = cls.getTypeParameters();
             for (int i = 0; i < cls.getTypeParameters().size() && i < globGicName.length; i++) {
                 genericMap.put(variables.get(i).getName(), globGicName[i]);