[Python] ModuleNotFoundError when packagename contains dots (#2992)

* feat(python): Support package names with dots

* feat(python): Fixing tests

* feat(python): Adding comment

* fix(python): Fixing indentation

* fix(python): Fixing indentation

Author: saigiridhar21

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

@@ -41,8 +41,8 @@ public class PythonClientCodegen extends DefaultCodegen implements CodegenConfig
     public static final String PACKAGE_URL = "packageUrl";
     public static final String DEFAULT_LIBRARY = "urllib3";
 
-    protected String packageName; // e.g. petstore_api
-    protected String packageVersion;
+    protected String packageName = "openapi_client";
+    protected String packageVersion = "1.0.0";
     protected String projectName; // for setup.py, e.g. petstore-api
     protected String packageUrl;
     protected String apiDocPath = "docs/";
@@ -177,8 +177,6 @@ public void processOpts() {
 
         if (additionalProperties.containsKey(CodegenConstants.PACKAGE_NAME)) {
             setPackageName((String) additionalProperties.get(CodegenConstants.PACKAGE_NAME));
-        } else {
-            setPackageName("openapi_client");
         }
 
         if (additionalProperties.containsKey(CodegenConstants.PROJECT_NAME)) {
@@ -191,9 +189,7 @@ public void processOpts() {
 
         if (additionalProperties.containsKey(CodegenConstants.PACKAGE_VERSION)) {
             setPackageVersion((String) additionalProperties.get(CodegenConstants.PACKAGE_VERSION));
-        } else {
-            setPackageVersion("1.0.0");
-        }
+        } 
 
         Boolean generateSourceCodeOnly = false;
         if (additionalProperties.containsKey(CodegenConstants.SOURCECODEONLY_GENERATION)) {
@@ -241,10 +237,22 @@ public void processOpts() {
         supportingFiles.add(new SupportingFile("__init__package.mustache", packagePath(), "__init__.py"));
         supportingFiles.add(new SupportingFile("__init__model.mustache", packagePath() + File.separatorChar + modelPackage, "__init__.py"));
         supportingFiles.add(new SupportingFile("__init__api.mustache", packagePath() + File.separatorChar + apiPackage, "__init__.py"));
+
+        // If the package name consists of dots(openapi.client), then we need to create the directory structure like openapi/client with __init__ files.
+        String[] packageNameSplits = packageName.split("\\.");
+        String currentPackagePath = "";
+        for (int i = 0; i < packageNameSplits.length-1; i++) {
+            if (i > 0) {
+                currentPackagePath = currentPackagePath + File.separatorChar;
+            }
+            currentPackagePath = currentPackagePath + packageNameSplits[i];
+            supportingFiles.add(new SupportingFile("__init__.mustache", currentPackagePath, "__init__.py"));
+        }
+
         supportingFiles.add(new SupportingFile("exceptions.mustache", packagePath(), "exceptions.py"));
 
         if (Boolean.FALSE.equals(excludeTests)) {
-            supportingFiles.add(new SupportingFile("__init__test.mustache", testFolder, "__init__.py"));
+            supportingFiles.add(new SupportingFile("__init__.mustache", testFolder, "__init__.py"));
         }
 
         supportingFiles.add(new SupportingFile("api_client.mustache", packagePath(), "api_client.py"));