diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java
index 65e1121927d0..541986aaf1f9 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java
@@ -86,7 +86,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/others/java/okhttp-gson-oneOf/src/main/java/org/openapitools/client/JSON.java b/samples/client/others/java/okhttp-gson-oneOf/src/main/java/org/openapitools/client/JSON.java
index 3fc3f4c62307..c6b151d0ccc0 100644
--- a/samples/client/others/java/okhttp-gson-oneOf/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/others/java/okhttp-gson-oneOf/src/main/java/org/openapitools/client/JSON.java
@@ -86,7 +86,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/JSON.java b/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/JSON.java
index 417a0011024a..999628dc1f76 100644
--- a/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/JSON.java
@@ -86,7 +86,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/JSON.java b/samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/JSON.java
index 6791d767d970..26a29cc295d2 100644
--- a/samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/JSON.java
@@ -115,7 +115,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/JSON.java b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/JSON.java
index e069227577cc..f993e935c7aa 100644
--- a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/JSON.java
@@ -86,7 +86,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/JSON.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/JSON.java
index 3f5a7126f4d3..6d80edba2a7b 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/JSON.java
@@ -126,7 +126,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/JSON.java b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/JSON.java
index e069227577cc..f993e935c7aa 100644
--- a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/JSON.java
@@ -86,7 +86,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/JSON.java b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/JSON.java
index 4fd5aa31f9d5..cc08e8c32f43 100644
--- a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/JSON.java
@@ -86,7 +86,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/JSON.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/JSON.java
index 3f5a7126f4d3..6d80edba2a7b 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/JSON.java
@@ -126,7 +126,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/JSON.java b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/JSON.java
index e069227577cc..f993e935c7aa 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/JSON.java
@@ -86,7 +86,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/JSON.java b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/JSON.java
index e069227577cc..f993e935c7aa 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/JSON.java
@@ -86,7 +86,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java
index dc729b10c5eb..631f1fdaba8c 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java
@@ -222,7 +222,7 @@ private static Class getClassByDiscriminator(Map classByDiscriminatorValue, Stri
         return clazz;
     }
 
-    {
+    static {
         GsonBuilder gsonBuilder = createGson();
         gsonBuilder.registerTypeAdapter(Date.class, dateTypeAdapter);
         gsonBuilder.registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter);