Skip examples on complex body in Java (#8887)

* Skip examples on complex body in Java

This removes complex examples in Java which would not result in valid
code.

* Warn example being skip

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

@@ -23,10 +23,13 @@ import io.swagger.v3.oas.models.Operation;
 import io.swagger.v3.oas.models.PathItem;
 import io.swagger.v3.oas.models.examples.Example;
 import io.swagger.v3.oas.models.media.ArraySchema;
+import io.swagger.v3.oas.models.media.Content;
 import io.swagger.v3.oas.models.media.ComposedSchema;
+import io.swagger.v3.oas.models.media.MediaType;
 import io.swagger.v3.oas.models.media.Schema;
 import io.swagger.v3.oas.models.media.StringSchema;
 import io.swagger.v3.oas.models.parameters.Parameter;
+import io.swagger.v3.oas.models.parameters.RequestBody;
 import io.swagger.v3.oas.models.servers.Server;
 import io.swagger.v3.parser.util.SchemaTypeUtil;
 import org.apache.commons.io.FilenameUtils;
@@ -984,6 +987,49 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
         setParameterExampleValue(codegenParameter);
     }
 
+    /**
+     * Return the example value of the parameter. Overrides the parent method in DefaultCodegen
+     * to not set examples on complex models, as they don't compile properly.
+     *
+     * @param codegenParameter Codegen parameter
+     * @param requestBody      Request body
+     */
+    @Override
+    public void setParameterExampleValue(CodegenParameter codegenParameter, RequestBody requestBody) {
+        Boolean isModel = (codegenParameter.isModel || (codegenParameter.isContainer && codegenParameter.getItems().isModel));
+
+        Content content = requestBody.getContent();
+
+        if (content.size() > 1) {
+            // @see ModelUtils.getSchemaFromContent()
+            LOGGER.warn("Multiple MediaTypes found, using only the first one");
+        }
+
+        MediaType mediaType = content.values().iterator().next();
+        if (mediaType.getExample() != null) {
+            if (isModel) {
+                LOGGER.warn("Ignoring complex example on request body");
+            } else {
+                codegenParameter.example = mediaType.getExample().toString();
+                return;
+            }
+        }
+
+        if (mediaType.getExamples() != null && !mediaType.getExamples().isEmpty()) {
+            Example example = mediaType.getExamples().values().iterator().next();
+            if (example.getValue() != null) {
+                if (isModel) {
+                    LOGGER.warn("Ignoring complex example on request body");
+                } else {
+                    codegenParameter.example = example.getValue().toString();
+                    return;
+                }
+            }
+        }
+
+        setParameterExampleValue(codegenParameter);
+    }
+
     @Override
     public void setParameterExampleValue(CodegenParameter p) {
         String example;

modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-with-http-signature.yaml

@@ -1146,6 +1146,13 @@ components:
             type: array
             items:
               $ref: '#/components/schemas/User'
+          examples:
+            simple-list:
+              summary: Simple list example
+              description: Should not get into code examples
+              value:
+                - username: foo
+                - username: bar
       description: List of user object
       required: true
     Client:

samples/openapi3/client/petstore/java/jersey2-java8/api/openapi.yaml

@@ -1257,6 +1257,13 @@ components:
     UserArray:
       content:
         application/json:
+          examples:
+            simple-list:
+              description: Should not get into code examples
+              summary: Simple list example
+              value:
+              - username: foo
+              - username: bar
           schema:
             items:
               $ref: '#/components/schemas/User'

samples/openapi3/client/petstore/java/native/api/openapi.yaml

@@ -1257,6 +1257,13 @@ components:
     UserArray:
       content:
         application/json:
+          examples:
+            simple-list:
+              description: Should not get into code examples
+              summary: Simple list example
+              value:
+              - username: foo
+              - username: bar
           schema:
             items:
               $ref: '#/components/schemas/User'