[main-lts] Add initialize empty collection parameter

client/deployment/src/main/java/io/quarkiverse/openapi/generator/deployment/CodegenConfig.java

@@ -69,6 +69,7 @@ enum ConfigName {
         PART_FILENAME_VALUE("part-filename-value"),
         USE_FIELD_NAME_IN_PART_FILENAME("use-field-name-in-part-filename"),
         ADDITIONAL_PROPERTIES_AS_ATTRIBUTE("additional-properties-as-attribute"),
+        INITIALIZE_EMPTY_COLLECTIONS("initialize-empty-collections"),
         ADDITIONAL_REQUEST_ARGS("additional-request-args"),
         REMOVE_OPERATION_ID_PREFIX("remove-operation-id-prefix"),
         REMOVE_OPERATION_ID_PREFIX_DELIMITER("remove-operation-id-prefix-delimiter"),

client/deployment/src/main/java/io/quarkiverse/openapi/generator/deployment/CommonItemConfig.java

@@ -183,4 +183,10 @@ public interface CommonItemConfig {
      */
     @WithName("additional-properties-as-attribute")
     Optional<String> additionalPropertiesAsAttribute();
+
+    /**
+     * Initialise collections as empty instead of null
+     */
+    @WithName("initialize-empty-collections")
+    Optional<String> initializeEmptyCollections();
 }

client/deployment/src/main/java/io/quarkiverse/openapi/generator/deployment/codegen/OpenApiGeneratorCodeGenBase.java

@@ -335,6 +335,12 @@ protected void generate(OpenApiGeneratorOptions options) {
                 .ifPresent(generator::withMutinyReturnTypes);
 
         generator.withAdditionalPropertiesAsAttribute(additionalPropertiesAsAttribute);
+
+        Boolean initialiseEmptyCollection = getValues(smallRyeConfig, openApiFilePath,
+                CodegenConfig.ConfigName.INITIALIZE_EMPTY_COLLECTIONS, Boolean.class)
+                .orElse(Boolean.FALSE);
+        generator.withInitializeEmptyCollections(initialiseEmptyCollection);
+
         GlobalSettings.setProperty(
                 OpenApiClientGeneratorWrapper.SUPPORTS_ADDITIONAL_PROPERTIES_AS_ATTRIBUTE,
                 additionalPropertiesAsAttribute.toString());

client/deployment/src/main/java/io/quarkiverse/openapi/generator/deployment/wrapper/OpenApiClientGeneratorWrapper.java

@@ -89,6 +89,7 @@ private void setDefaults() {
         // Set default values directly here
         this.configurator.addAdditionalProperty("additionalApiTypeAnnotations", new String[0]);
         this.configurator.addAdditionalProperty("additionalPropertiesAsAttribute", FALSE);
+        this.configurator.addAdditionalProperty("initializeEmptyCollections", FALSE);
         this.configurator.addAdditionalProperty("additionalEnumTypeUnexpectedMember", FALSE);
         this.configurator.addAdditionalProperty("additionalEnumTypeUnexpectedMemberName", "");
         this.configurator.addAdditionalProperty("additionalEnumTypeUnexpectedMemberStringValue", "");
@@ -368,6 +369,10 @@ public void withAdditionalPropertiesAsAttribute(final Boolean enable) {
         this.configurator.addAdditionalProperty("additionalPropertiesAsAttribute", Optional.ofNullable(enable).orElse(FALSE));
     }
 
+    public void withInitializeEmptyCollections(final Boolean enable) {
+        this.configurator.addAdditionalProperty("initializeEmptyCollections", Optional.ofNullable(enable).orElse(FALSE));
+    }
+
     public static String transformToSafeConfigKey(String input) {
         return input.replaceAll("[^a-zA-Z0-9\\-_]", "_");
     }

client/deployment/src/main/resources/templates/libraries/microprofile/pojo.qute

@@ -39,7 +39,7 @@ public class {m.classname} {#if m.parent}extends {m.parent}{/if}{#if serializabl
     {/if}
     {#if v.hasValidation || v.required}{#include beanValidation.qute p=v/}{/if}
     {#if v.isContainer}
-    private {v.datatypeWithEnum} {v.name}{#if v.required && v.defaultValue} = {v.defaultValue}{/if};
+    private {v.datatypeWithEnum} {v.name}{#if v.required && v.defaultValue} = {v.defaultValue}{#else if v.isArray && initializeEmptyCollections} = new {#if v.uniqueItems}LinkedHashSet{/if}{#if !v.uniqueItems}ArrayList{/if}<>(){#else if v.isMap && initializeEmptyCollections} = new HashMap<>(){/if};
     {#else}
     private {v.datatypeWithEnum} {v.name}{#if v.defaultValue} = {v.defaultValue}{/if};
     {/if}

client/integration-tests/initialize-empty-collections/pom.xml

@@ -0,0 +1,89 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <parent>
+    <artifactId>quarkus-openapi-generator-integration-tests</artifactId>
+    <groupId>io.quarkiverse.openapi.generator</groupId>
+    <version>3.0.0-lts-SNAPSHOT</version>
+  </parent>
+  <modelVersion>4.0.0</modelVersion>
+
+  <artifactId>quarkus-openapi-generator-it-initialize-empty-collections</artifactId>
+  <name>Quarkus - OpenAPI Generator - Integration Tests - Client - Initialize Empty Collections</name>
+
+  <dependencies>
+    <dependency>
+      <groupId>io.quarkiverse.openapi.generator</groupId>
+      <artifactId>quarkus-openapi-generator</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.assertj</groupId>
+      <artifactId>assertj-core</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-junit5</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>io.quarkus</groupId>
+        <artifactId>quarkus-maven-plugin</artifactId>
+        <extensions>true</extensions>
+        <executions>
+          <execution>
+            <goals>
+              <goal>build</goal>
+              <goal>generate-code</goal>
+              <goal>generate-code-tests</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+  <profiles>
+    <profile>
+      <id>native-image</id>
+      <activation>
+        <property>
+          <name>native</name>
+        </property>
+      </activation>
+      <build>
+        <plugins>
+          <plugin>
+            <artifactId>maven-surefire-plugin</artifactId>
+            <configuration>
+              <skipTests>${native.surefire.skip}</skipTests>
+            </configuration>
+          </plugin>
+          <plugin>
+            <artifactId>maven-failsafe-plugin</artifactId>
+            <executions>
+              <execution>
+                <goals>
+                  <goal>integration-test</goal>
+                  <goal>verify</goal>
+                </goals>
+                <configuration>
+                  <systemPropertyVariables>
+                    <native.image.path>${project.build.directory}/${project.build.finalName}-runner</native.image.path>
+                    <java.util.logging.manager>org.jboss.logmanager.LogManager</java.util.logging.manager>
+                    <maven.home>${maven.home}</maven.home>
+                  </systemPropertyVariables>
+                </configuration>
+              </execution>
+            </executions>
+          </plugin>
+        </plugins>
+      </build>
+      <properties>
+        <quarkus.package.type>native</quarkus.package.type>
+      </properties>
+    </profile>
+  </profiles>
+
+</project>