Non-null Lists should be initialized

Author: reda-alaoui

core/src/main/java/com/cosium/json_schema_to_java_record/JsonSchemaContent.java

@@ -156,8 +156,17 @@ public TypeName writeJavaType(
         constructorBuilder.addParameter(parameterSpecBuilder.build());
 
         if (!propertyType.isPrimitive() && required.contains(propertyName)) {
-          compactConstructorBuilder.addStatement(
-              "$T.requireNonNull($N)", Objects.class, propertyName);
+          if (isList(propertyType)) {
+            compactConstructorBuilder.addStatement(
+                "$N = $T.ofNullable($N).orElseGet($T::of)",
+                propertyName,
+                Optional.class,
+                propertyName,
+                List.class);
+          } else {
+            compactConstructorBuilder.addStatement(
+                "$T.requireNonNull($N)", Objects.class, propertyName);
+          }
         }
       }
       typeBuilder
@@ -181,6 +190,18 @@ public TypeName writeJavaType(
     return className;
   }
 
+  private boolean isList(TypeName type) {
+    ClassName className;
+    if (type instanceof ClassName classNameCandidate) {
+      className = classNameCandidate;
+    } else if (type instanceof ParameterizedTypeName parameterizedTypeName) {
+      className = parameterizedTypeName.rawType();
+    } else {
+      return false;
+    }
+    return className.canonicalName().equals(List.class.getCanonicalName());
+  }
+
   private void addJsonRelatedAnnotations(
       ParameterSpec.Builder parameterBuilder, String propertyName) {
 

tests/src/test/java/com/cosium/json_schema_to_java_record_tests/case1/package-info.java

@@ -5,8 +5,11 @@
     schemaRootFileLocations =
         @JsonSchemaFileLocation(
             moduleAndPackage = "com.cosium.json_schema_to_java_record_tests.case1",
-            relativeName = "customer.json"),
+            relativeName = "customers.json"),
     schemaConfigurations = {
+      @JsonSchemaConfiguration(
+          schemaId = "customers",
+          javaTypeQualifiedName = "com.cosium.json_schema_to_java_record_tests.case1.Customers"),
       @JsonSchemaConfiguration(
           schemaId = "customer",
           javaTypeQualifiedName = "com.cosium.json_schema_to_java_record_tests.case1.Customer"),

tests/src/test/resources/com/cosium/json_schema_to_java_record_tests/case1/customers.json

@@ -0,0 +1,16 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "customers",
+  "type": "object",
+  "properties": {
+    "list": {
+      "type": "array",
+      "items": {
+        "$ref": "classpath:/com/cosium/json_schema_to_java_record_tests/case1/customer.json"
+      }
+    }
+  },
+  "required": [
+    "list"
+  ]
+}