[C++][RESTSDK] models header fix (#2750)

* Fix issue including header, the filename not the class name should be used to import a header file.

* Include header file name, not class name.

Header file name and class name differ.

* Update petstore samples

Author: dan-drl

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestSdkClientCodegen.java

@@ -208,7 +208,7 @@ public String toModelImport(String name) {
         if (importMapping.containsKey(name)) {
             return importMapping.get(name);
         } else {
-            return "#include \"" + sanitizeName(name) + ".h\"";
+            return "#include \"" + toModelFilename(name) + ".h\"";
         }
     }
 

modules/openapi-generator/src/main/resources/cpp-rest-sdk-client/model-source.mustache

@@ -1,7 +1,7 @@
 {{>licenseInfo}}
 {{#models}}{{#model}}
 
-#include "{{classname}}.h"
+#include "{{classFilename}}.h"
 
 {{#modelNamespaceDeclarations}}
 namespace {{this}} {

samples/client/petstore/cpp-restsdk/.openapi-generator/VERSION

@@ -1 +1 @@
-3.3.4
+4.0.0-SNAPSHOT