diff --git a/modules/swagger-codegen/src/main/resources/Javascript/api.mustache b/modules/swagger-codegen/src/main/resources/Javascript/api.mustache
index 0de415ad049..fedb65f421b 100644
--- a/modules/swagger-codegen/src/main/resources/Javascript/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/Javascript/api.mustache
@@ -27,7 +27,7 @@
    * <description></description>
    * @alias module:<#invokerPackage><&invokerPackage>/</invokerPackage><#apiPackage><apiPackage>/</apiPackage><classname>
    * @class
-   * @param {module:<#invokerPackage><&invokerPackage>/</invokerPackage>ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:<#invokerPackage><&invokerPackage>/</invokerPackage>ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:<#invokerPackage><&invokerPackage>/</invokerPackage>ApiClient#instance} if unspecified.
    */
 </emitJSDoc>  var exports = function(apiClient) {
diff --git a/modules/swagger-codegen/src/main/resources/Javascript/es6/api.mustache b/modules/swagger-codegen/src/main/resources/Javascript/es6/api.mustache
index f913650b614..0615a0461d4 100644
--- a/modules/swagger-codegen/src/main/resources/Javascript/es6/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/Javascript/es6/api.mustache
@@ -17,7 +17,7 @@ export default class <classname> {
     * <description></description>
     * @alias module:<#invokerPackage><&invokerPackage>/</invokerPackage><#apiPackage><apiPackage>/</apiPackage><classname>
     * @class
-    * @param {module:<#invokerPackage><&invokerPackage>/</invokerPackage>ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:<#invokerPackage><&invokerPackage>/</invokerPackage>ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:<#invokerPackage><&invokerPackage>/</invokerPackage>ApiClient#instance} if unspecified.
     */</emitJSDoc>
     constructor(apiClient) {
diff --git a/samples/client/petstore-security-test/javascript/src/api/FakeApi.js b/samples/client/petstore-security-test/javascript/src/api/FakeApi.js
index 7571d260f22..4a5d37f908e 100644
--- a/samples/client/petstore-security-test/javascript/src/api/FakeApi.js
+++ b/samples/client/petstore-security-test/javascript/src/api/FakeApi.js
@@ -41,7 +41,7 @@
    * Constructs a new FakeApi. 
    * @alias module:api/FakeApi
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {
diff --git a/samples/client/petstore/javascript-es6/src/api/FakeApi.js b/samples/client/petstore/javascript-es6/src/api/FakeApi.js
index df4371ba8f3..99741813c03 100644
--- a/samples/client/petstore/javascript-es6/src/api/FakeApi.js
+++ b/samples/client/petstore/javascript-es6/src/api/FakeApi.js
@@ -30,7 +30,7 @@ export default class FakeApi {
     * Constructs a new FakeApi. 
     * @alias module:api/FakeApi
     * @class
-    * @param {module:ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:ApiClient#instance} if unspecified.
     */
     constructor(apiClient) {
diff --git a/samples/client/petstore/javascript-es6/src/api/Fake_classname_tags123Api.js b/samples/client/petstore/javascript-es6/src/api/Fake_classname_tags123Api.js
index 7c4e36454cb..1240fbf42c1 100644
--- a/samples/client/petstore/javascript-es6/src/api/Fake_classname_tags123Api.js
+++ b/samples/client/petstore/javascript-es6/src/api/Fake_classname_tags123Api.js
@@ -26,7 +26,7 @@ export default class Fake_classname_tags123Api {
     * Constructs a new Fake_classname_tags123Api. 
     * @alias module:api/Fake_classname_tags123Api
     * @class
-    * @param {module:ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:ApiClient#instance} if unspecified.
     */
     constructor(apiClient) {
diff --git a/samples/client/petstore/javascript-es6/src/api/PetApi.js b/samples/client/petstore/javascript-es6/src/api/PetApi.js
index e59d99bcc38..aea4c0049b2 100644
--- a/samples/client/petstore/javascript-es6/src/api/PetApi.js
+++ b/samples/client/petstore/javascript-es6/src/api/PetApi.js
@@ -27,7 +27,7 @@ export default class PetApi {
     * Constructs a new PetApi. 
     * @alias module:api/PetApi
     * @class
-    * @param {module:ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:ApiClient#instance} if unspecified.
     */
     constructor(apiClient) {
diff --git a/samples/client/petstore/javascript-es6/src/api/StoreApi.js b/samples/client/petstore/javascript-es6/src/api/StoreApi.js
index b70fc4c0883..28fe086c2e4 100644
--- a/samples/client/petstore/javascript-es6/src/api/StoreApi.js
+++ b/samples/client/petstore/javascript-es6/src/api/StoreApi.js
@@ -26,7 +26,7 @@ export default class StoreApi {
     * Constructs a new StoreApi. 
     * @alias module:api/StoreApi
     * @class
-    * @param {module:ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:ApiClient#instance} if unspecified.
     */
     constructor(apiClient) {
diff --git a/samples/client/petstore/javascript-es6/src/api/UserApi.js b/samples/client/petstore/javascript-es6/src/api/UserApi.js
index 54c9b110d7b..600ca5f4200 100644
--- a/samples/client/petstore/javascript-es6/src/api/UserApi.js
+++ b/samples/client/petstore/javascript-es6/src/api/UserApi.js
@@ -26,7 +26,7 @@ export default class UserApi {
     * Constructs a new UserApi. 
     * @alias module:api/UserApi
     * @class
-    * @param {module:ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:ApiClient#instance} if unspecified.
     */
     constructor(apiClient) {
diff --git a/samples/client/petstore/javascript-promise-es6/src/api/FakeApi.js b/samples/client/petstore/javascript-promise-es6/src/api/FakeApi.js
index a199f908642..9bcf6796fa3 100644
--- a/samples/client/petstore/javascript-promise-es6/src/api/FakeApi.js
+++ b/samples/client/petstore/javascript-promise-es6/src/api/FakeApi.js
@@ -30,7 +30,7 @@ export default class FakeApi {
     * Constructs a new FakeApi. 
     * @alias module:api/FakeApi
     * @class
-    * @param {module:ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:ApiClient#instance} if unspecified.
     */
     constructor(apiClient) {
diff --git a/samples/client/petstore/javascript-promise-es6/src/api/Fake_classname_tags123Api.js b/samples/client/petstore/javascript-promise-es6/src/api/Fake_classname_tags123Api.js
index 43f98a3e94f..9ce405845a5 100644
--- a/samples/client/petstore/javascript-promise-es6/src/api/Fake_classname_tags123Api.js
+++ b/samples/client/petstore/javascript-promise-es6/src/api/Fake_classname_tags123Api.js
@@ -26,7 +26,7 @@ export default class Fake_classname_tags123Api {
     * Constructs a new Fake_classname_tags123Api. 
     * @alias module:api/Fake_classname_tags123Api
     * @class
-    * @param {module:ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:ApiClient#instance} if unspecified.
     */
     constructor(apiClient) {
diff --git a/samples/client/petstore/javascript-promise-es6/src/api/PetApi.js b/samples/client/petstore/javascript-promise-es6/src/api/PetApi.js
index 53e385ef2cd..7e79f14a48f 100644
--- a/samples/client/petstore/javascript-promise-es6/src/api/PetApi.js
+++ b/samples/client/petstore/javascript-promise-es6/src/api/PetApi.js
@@ -27,7 +27,7 @@ export default class PetApi {
     * Constructs a new PetApi. 
     * @alias module:api/PetApi
     * @class
-    * @param {module:ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:ApiClient#instance} if unspecified.
     */
     constructor(apiClient) {
diff --git a/samples/client/petstore/javascript-promise-es6/src/api/StoreApi.js b/samples/client/petstore/javascript-promise-es6/src/api/StoreApi.js
index 0b55929a8a4..689d4ffb638 100644
--- a/samples/client/petstore/javascript-promise-es6/src/api/StoreApi.js
+++ b/samples/client/petstore/javascript-promise-es6/src/api/StoreApi.js
@@ -26,7 +26,7 @@ export default class StoreApi {
     * Constructs a new StoreApi. 
     * @alias module:api/StoreApi
     * @class
-    * @param {module:ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:ApiClient#instance} if unspecified.
     */
     constructor(apiClient) {
diff --git a/samples/client/petstore/javascript-promise-es6/src/api/UserApi.js b/samples/client/petstore/javascript-promise-es6/src/api/UserApi.js
index 1c1fe593e26..c2c19d2f311 100644
--- a/samples/client/petstore/javascript-promise-es6/src/api/UserApi.js
+++ b/samples/client/petstore/javascript-promise-es6/src/api/UserApi.js
@@ -26,7 +26,7 @@ export default class UserApi {
     * Constructs a new UserApi. 
     * @alias module:api/UserApi
     * @class
-    * @param {module:ApiClient} apiClient Optional API client implementation to use,
+    * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
     * default to {@link module:ApiClient#instance} if unspecified.
     */
     constructor(apiClient) {
diff --git a/samples/client/petstore/javascript-promise/src/api/FakeApi.js b/samples/client/petstore/javascript-promise/src/api/FakeApi.js
index eb95b4d4712..0b3b9c24e2f 100644
--- a/samples/client/petstore/javascript-promise/src/api/FakeApi.js
+++ b/samples/client/petstore/javascript-promise/src/api/FakeApi.js
@@ -41,7 +41,7 @@
    * Constructs a new FakeApi. 
    * @alias module:api/FakeApi
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {
diff --git a/samples/client/petstore/javascript-promise/src/api/Fake_classname_tags123Api.js b/samples/client/petstore/javascript-promise/src/api/Fake_classname_tags123Api.js
index 0fd0a3001d3..691fa430cb4 100644
--- a/samples/client/petstore/javascript-promise/src/api/Fake_classname_tags123Api.js
+++ b/samples/client/petstore/javascript-promise/src/api/Fake_classname_tags123Api.js
@@ -41,7 +41,7 @@
    * Constructs a new Fake_classname_tags123Api. 
    * @alias module:api/Fake_classname_tags123Api
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {
diff --git a/samples/client/petstore/javascript-promise/src/api/PetApi.js b/samples/client/petstore/javascript-promise/src/api/PetApi.js
index 6aada6cbc14..655f36436fb 100644
--- a/samples/client/petstore/javascript-promise/src/api/PetApi.js
+++ b/samples/client/petstore/javascript-promise/src/api/PetApi.js
@@ -41,7 +41,7 @@
    * Constructs a new PetApi. 
    * @alias module:api/PetApi
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {
diff --git a/samples/client/petstore/javascript-promise/src/api/StoreApi.js b/samples/client/petstore/javascript-promise/src/api/StoreApi.js
index 48f7bbfce43..dc39ad33499 100644
--- a/samples/client/petstore/javascript-promise/src/api/StoreApi.js
+++ b/samples/client/petstore/javascript-promise/src/api/StoreApi.js
@@ -41,7 +41,7 @@
    * Constructs a new StoreApi. 
    * @alias module:api/StoreApi
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {
diff --git a/samples/client/petstore/javascript-promise/src/api/UserApi.js b/samples/client/petstore/javascript-promise/src/api/UserApi.js
index 05f37528d95..3d6e216aaa4 100644
--- a/samples/client/petstore/javascript-promise/src/api/UserApi.js
+++ b/samples/client/petstore/javascript-promise/src/api/UserApi.js
@@ -41,7 +41,7 @@
    * Constructs a new UserApi. 
    * @alias module:api/UserApi
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {
diff --git a/samples/client/petstore/javascript/src/api/FakeApi.js b/samples/client/petstore/javascript/src/api/FakeApi.js
index 156a91d18fc..f7621dc00c9 100644
--- a/samples/client/petstore/javascript/src/api/FakeApi.js
+++ b/samples/client/petstore/javascript/src/api/FakeApi.js
@@ -41,7 +41,7 @@
    * Constructs a new FakeApi. 
    * @alias module:api/FakeApi
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {
diff --git a/samples/client/petstore/javascript/src/api/Fake_classname_tags123Api.js b/samples/client/petstore/javascript/src/api/Fake_classname_tags123Api.js
index 66dd5358704..4ade0b35502 100644
--- a/samples/client/petstore/javascript/src/api/Fake_classname_tags123Api.js
+++ b/samples/client/petstore/javascript/src/api/Fake_classname_tags123Api.js
@@ -41,7 +41,7 @@
    * Constructs a new Fake_classname_tags123Api. 
    * @alias module:api/Fake_classname_tags123Api
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {
diff --git a/samples/client/petstore/javascript/src/api/PetApi.js b/samples/client/petstore/javascript/src/api/PetApi.js
index dffd8db2bcb..89e23ba64c7 100644
--- a/samples/client/petstore/javascript/src/api/PetApi.js
+++ b/samples/client/petstore/javascript/src/api/PetApi.js
@@ -41,7 +41,7 @@
    * Constructs a new PetApi. 
    * @alias module:api/PetApi
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {
diff --git a/samples/client/petstore/javascript/src/api/StoreApi.js b/samples/client/petstore/javascript/src/api/StoreApi.js
index 8be29a01f55..0c303c3ac20 100644
--- a/samples/client/petstore/javascript/src/api/StoreApi.js
+++ b/samples/client/petstore/javascript/src/api/StoreApi.js
@@ -41,7 +41,7 @@
    * Constructs a new StoreApi. 
    * @alias module:api/StoreApi
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {
diff --git a/samples/client/petstore/javascript/src/api/UserApi.js b/samples/client/petstore/javascript/src/api/UserApi.js
index 829b5ea4bc9..183c05b4871 100644
--- a/samples/client/petstore/javascript/src/api/UserApi.js
+++ b/samples/client/petstore/javascript/src/api/UserApi.js
@@ -41,7 +41,7 @@
    * Constructs a new UserApi. 
    * @alias module:api/UserApi
    * @class
-   * @param {module:ApiClient} apiClient Optional API client implementation to use,
+   * @param {module:ApiClient} [apiClient] Optional API client implementation to use,
    * default to {@link module:ApiClient#instance} if unspecified.
    */
   var exports = function(apiClient) {