diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java
index 74b235f1e73d..56808a6efbde 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java
@@ -781,7 +781,7 @@ public String toInstantiationType(Schema p) {
     public String getTypeDeclaration(Schema p) {
         if (p instanceof ArraySchema) {
             return getArrayTypeDeclaration((ArraySchema) p);
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             // Should we also support maps of maps?
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractGoCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractGoCodegen.java
index 774c4eab1934..32315bc64756 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractGoCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractGoCodegen.java
@@ -228,7 +228,7 @@ public String getTypeDeclaration(Schema p) {
             Schema inner = ap.getItems();
             return "[]" + getTypeDeclaration(inner);
         }
-        else if (p instanceof MapSchema) {
+        else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractKotlinCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractKotlinCodegen.java
index 7095ffad6ad6..7e9d09a69f81 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractKotlinCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractKotlinCodegen.java
@@ -263,7 +263,7 @@ public String getSchemaType(Schema p) {
     public String getTypeDeclaration(Schema p) {
         if (p instanceof ArraySchema) {
             return getArrayTypeDeclaration((ArraySchema) p);
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractPhpCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractPhpCodegen.java
index c9ac464189bc..722522b5472c 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractPhpCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractPhpCodegen.java
@@ -308,7 +308,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getTypeDeclaration(inner) + "[]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getSchemaType(p) + "[string," + getTypeDeclaration(inner) + "]";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractScalaCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractScalaCodegen.java
index ae1a2532c64f..cebd7b42be59 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractScalaCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractScalaCodegen.java
@@ -160,7 +160,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractTypeScriptClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractTypeScriptClientCodegen.java
index 23ad7b8d8a9e..a1b15145e099 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractTypeScriptClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractTypeScriptClientCodegen.java
@@ -215,7 +215,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "<" + getTypeDeclaration(inner) + ">";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return "{ [key: string]: " + getTypeDeclaration(inner) + "; }";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AkkaScalaClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AkkaScalaClientCodegen.java
index 582b37374691..699f31706bce 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AkkaScalaClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AkkaScalaClientCodegen.java
@@ -258,7 +258,7 @@ public String toDefaultValue(Schema p) {
             return "null";
         } else if (p instanceof IntegerSchema) {
             return "null";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema ap = (MapSchema) p;
             String inner = getSchemaType((Schema) ap.getAdditionalProperties());
             return "Map[String, " + inner + "].empty ";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AndroidClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AndroidClientCodegen.java
index 36b1458b833d..95c103c10425 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AndroidClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AndroidClientCodegen.java
@@ -171,7 +171,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "<" + getTypeDeclaration(inner) + ">";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/BashClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/BashClientCodegen.java
index 86c7c669403a..addd3d1bfceb 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/BashClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/BashClientCodegen.java
@@ -370,7 +370,7 @@ public String getTypeDeclaration(Schema p) {
       Schema inner = ap.getItems();
       return getSchemaType(p) + "[" + getTypeDeclaration(inner) + "]";
     }
-    else if (p instanceof MapSchema) {
+    else if (isMapSchema(p)) {
       MapSchema mp = (MapSchema) p;
       Schema inner = (Schema) mp.getAdditionalProperties();
       return getSchemaType(p) + "[String, " + getTypeDeclaration(inner) + "]";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ConfluenceWikiCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ConfluenceWikiCodegen.java
index a971b7172ff2..db819fe74ed0 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ConfluenceWikiCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ConfluenceWikiCodegen.java
@@ -74,7 +74,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java
index 0b576656c327..81e4aafdafae 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java
@@ -265,7 +265,7 @@ public String getTypeDeclaration(Schema p) {
             Schema inner = ap.getItems();
             return getSchemaType(p) + "<" + getTypeDeclaration(inner) + ">";
         }
-        if (p instanceof MapSchema) {
+        if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getSchemaType(p) + "<std::string, " + getTypeDeclaration(inner) + ">";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppQt5ClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppQt5ClientCodegen.java
index 30ce574ab2d4..b4da078482c9 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppQt5ClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppQt5ClientCodegen.java
@@ -288,7 +288,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "<" + getTypeDeclaration(inner) + ">*";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getSchemaType(p) + "<QString, " + getTypeDeclaration(inner) + ">*";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestClientCodegen.java
index e7f6cb291493..5fa6b0760dc2 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestClientCodegen.java
@@ -280,7 +280,7 @@ public String getTypeDeclaration(Schema p) {
             Schema inner = ap.getItems();
             return getSchemaType(p) + "<" + getTypeDeclaration(inner) + ">";
         }
-        if (p instanceof MapSchema) {
+        if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getSchemaType(p) + "<utility::string_t, " + getTypeDeclaration(inner) + ">";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestbedServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestbedServerCodegen.java
index d0f0a9ff8d98..30d817a4e4e9 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestbedServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestbedServerCodegen.java
@@ -268,7 +268,7 @@ public String getTypeDeclaration(Schema p) {
             Schema inner = ap.getItems();
             return getSchemaType(p) + "<" + getTypeDeclaration(inner) + ">";
         }
-        if (p instanceof MapSchema) {
+        if (isMapSchema(p)) {
             Schema inner = (Schema) p.getAdditionalProperties();
             return getSchemaType(p) + "<std::string, " + getTypeDeclaration(inner) + ">";
         }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartClientCodegen.java
index a39651244dc4..ec671d4dfa89 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartClientCodegen.java
@@ -276,7 +276,7 @@ public String toApiFilename(String name) {
 
     @Override
     public String toDefaultValue(Schema p) {
-        if (p instanceof MapSchema) {
+        if (isMapSchema(p)) {
             return "{}";
         } else if (p instanceof ArraySchema) {
             return "[]";
@@ -290,7 +290,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "<" + getTypeDeclaration(inner) + ">";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java
index 164074429ea0..68666561c9a0 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java
@@ -421,7 +421,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return "%{optional(String.t) => " + getTypeDeclaration(inner) + "}";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/HaskellHttpClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/HaskellHttpClientCodegen.java
index 7f67cb005c65..3a67f6a84919 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/HaskellHttpClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/HaskellHttpClientCodegen.java
@@ -531,7 +531,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return "(Map.Map String " + getTypeDeclaration(inner) + ")";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/HaskellServantCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/HaskellServantCodegen.java
index 6ddcece0c275..47bfcaaa7c56 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/HaskellServantCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/HaskellServantCodegen.java
@@ -271,7 +271,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return "Map.Map String " + getTypeDeclaration(inner);
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavascriptClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavascriptClientCodegen.java
index 6377ffd6b2e8..2b0d1a9f1629 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavascriptClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavascriptClientCodegen.java
@@ -562,7 +562,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return "{String: " + getTypeDeclaration(inner) + "}";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ObjcClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ObjcClientCodegen.java
index 68b032d0d8c4..65035363e9a6 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ObjcClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ObjcClientCodegen.java
@@ -359,7 +359,7 @@ public String getTypeDeclaration(Schema p) {
                 }
                 return getSchemaType(p) + "<" + innerTypeDeclaration + ">*";
             }
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PerlClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PerlClientCodegen.java
index 74c22ce9a988..8bd6c74654c5 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PerlClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PerlClientCodegen.java
@@ -210,7 +210,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getSchemaType(p) + "[string," + getTypeDeclaration(inner) + "]";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSilexServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSilexServerCodegen.java
index 7c4741e45ad8..7f589209b8b5 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSilexServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSilexServerCodegen.java
@@ -138,7 +138,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getSchemaType(p) + "[string," + getTypeDeclaration(inner) + "]";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSlimServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSlimServerCodegen.java
index 6d0a195693c2..65209640981f 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSlimServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSlimServerCodegen.java
@@ -143,7 +143,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getTypeDeclaration(inner) + "[]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getSchemaType(p) + "[string," + getTypeDeclaration(inner) + "]";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSymfonyServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSymfonyServerCodegen.java
index 45bcdaf74f79..2d6b277d04e6 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSymfonyServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSymfonyServerCodegen.java
@@ -468,7 +468,7 @@ public String getTypeDeclaration(Schema p) {
             return getTypeDeclaration(inner);
         }
 
-        if (p instanceof MapSchema) {
+        if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getTypeDeclaration(inner);
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellClientCodegen.java
index 1a9c4af880f0..af011abcd618 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellClientCodegen.java
@@ -364,7 +364,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getTypeDeclaration(inner) + "[]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             // TODO not sure if the following map/hash declaration is correct
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonClientCodegen.java
index 2a68c2c57018..3c245c6cce3a 100755
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonClientCodegen.java
@@ -361,7 +361,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonFlaskConnexionServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonFlaskConnexionServerCodegen.java
index 7007ed0cf210..97337b2507c8 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonFlaskConnexionServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonFlaskConnexionServerCodegen.java
@@ -273,7 +273,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RClientCodegen.java
index 726ad5f43e54..30316cf25086 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RClientCodegen.java
@@ -278,7 +278,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getTypeDeclaration(inner);
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getTypeDeclaration(inner);
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubyClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubyClientCodegen.java
index 0ccca609a727..23004861fead 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubyClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubyClientCodegen.java
@@ -376,7 +376,7 @@ public String getTypeDeclaration(Schema schema) {
         if (schema instanceof ArraySchema) {
             Schema inner = ((ArraySchema) schema).getItems();
             return String.format("%s[%s]", getSchemaType(schema), getTypeDeclaration(inner));
-        } else if (schema instanceof MapSchema) {
+        } else if (isMapSchema(schema)) {
             Schema inner = (Schema) schema.getAdditionalProperties();
             return String.format("%s[String, %s]", getSchemaType(schema), getTypeDeclaration(inner));
         }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubyOnRailsServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubyOnRailsServerCodegen.java
index 80818db01c50..2ae7ec18e49f 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubyOnRailsServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubyOnRailsServerCodegen.java
@@ -204,7 +204,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getSchemaType(p) + "[string," + getTypeDeclaration(inner) + "]";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubySinatraServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubySinatraServerCodegen.java
index ff9c79396573..e24ade225e3c 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubySinatraServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubySinatraServerCodegen.java
@@ -123,7 +123,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return getSchemaType(p) + "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return getSchemaType(p) + "[string," + getTypeDeclaration(inner) + "]";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift3Codegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift3Codegen.java
index 8cd4a0d15768..9fa12d2b4a52 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift3Codegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift3Codegen.java
@@ -284,7 +284,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return "[String:" + getTypeDeclaration(inner) + "]";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift4Codegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift4Codegen.java
index 339a537a784c..7a1f7819b389 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift4Codegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift4Codegen.java
@@ -380,7 +380,7 @@ public String getTypeDeclaration(Schema prop) {
             ArraySchema ap = (ArraySchema) prop;
             Schema inner = ap.getItems();
             return "[" + getTypeDeclaration(inner) + "]";
-        } else if (prop instanceof MapSchema) {
+        } else if (isMapSchema(prop)) {
             MapSchema mp = (MapSchema) prop;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return "[String:" + getTypeDeclaration(inner) + "]";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/SwiftClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/SwiftClientCodegen.java
index 29a35d04cfd1..0bed035c5e52 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/SwiftClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/SwiftClientCodegen.java
@@ -262,7 +262,7 @@ public String getTypeDeclaration(Schema p) {
             ArraySchema ap = (ArraySchema) p;
             Schema inner = ap.getItems();
             return "[" + getTypeDeclaration(inner) + "]";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             MapSchema mp = (MapSchema) p;
             Schema inner = (Schema) mp.getAdditionalProperties();
             return "[String:" + getTypeDeclaration(inner) + "]";
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java
index 2e4eff4e388b..b223a3bf45b4 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java
@@ -100,7 +100,7 @@ public String getTypeDeclaration(Schema p) {
         if (p instanceof ArraySchema) {
             inner = ((ArraySchema) p).getItems();
             return this.getSchemaType(p) + "<" + this.getTypeDeclaration(inner) + ">";
-        } else if (p instanceof MapSchema) {
+        } else if (isMapSchema(p)) {
             inner = (Schema) p.getAdditionalProperties();
             return "{ [key: string]: " + this.getTypeDeclaration(inner) + "; }";
         } else if (p instanceof FileSchema) {