Avoid duplicate component generation by default

Author: TharmiganK

openapi-cli/src/main/java/io/ballerina/openapi/cmd/SubCmdBase.java

@@ -195,8 +195,8 @@ private void generateOpenAPI() {
     public abstract String getDefaultFileName();
 
     public Optional<OpenAPI> getFlattenOpenAPI(OpenAPI openAPI) {
-        // Flatten the OpenAPI definition with `flattenComposedSchemas: true` and `skipMatches: true`
-        InlineModelResolver inlineModelResolver = new InlineModelResolver(true, true);
+        // Flatten the OpenAPI definition with `flattenComposedSchemas: true` and `skipMatches: false`
+        InlineModelResolver inlineModelResolver = new InlineModelResolver(true, false);
         inlineModelResolver.flatten(openAPI);
         return Optional.of(openAPI);
     }

openapi-core/src/main/java/io/ballerina/openapi/core/generators/common/InlineModelResolver.java

@@ -116,9 +116,14 @@ private void flattenBody(String pathname, RequestBody body) {
                     if (model.getProperties() != null && !model.getProperties().isEmpty()) {
                         flattenProperties(model.getProperties(), pathname);
                         String modelName = resolveModelName(model.getTitle(), genericName);
-                        mediaType.setSchema(new Schema().$ref(modelName));
-                        addGenerated(modelName, model);
-                        openAPI.getComponents().addSchemas(modelName, model);
+                        String existing = matchGenerated(model);
+                        if (existing != null) {
+                            mediaType.setSchema(new Schema().$ref(existing));
+                        } else {
+                            mediaType.setSchema(new Schema().$ref(modelName));
+                            addGenerated(modelName, model);
+                            openAPI.getComponents().addSchemas(modelName, model);
+                        }
                     } else if (model instanceof ComposedSchema composedSchema) {
                         flattenComposedSchema(composedSchema, pathname);
                         if (model.get$ref() == null) {
@@ -170,9 +175,14 @@ private void flattenParams(String pathname, List<Parameter> parameters) {
                         if (model.getProperties() != null && !model.getProperties().isEmpty()) {
                             flattenProperties(model.getProperties(), pathname);
                             String modelName = resolveModelName(model.getTitle(), parameter.getName());
-                            parameter.setSchema(new Schema().$ref(modelName));
-                            addGenerated(modelName, model);
-                            openAPI.getComponents().addSchemas(modelName, model);
+                            String existing = matchGenerated(model);
+                            if (existing != null) {
+                                parameter.setSchema(new Schema().$ref(existing));
+                            } else {
+                                parameter.setSchema(new Schema().$ref(modelName));
+                                addGenerated(modelName, model);
+                                openAPI.getComponents().addSchemas(modelName, model);
+                            }
                         }
                     }
                 } else if (model instanceof ComposedSchema) {