Emit create() factory methods with generic return type

Fixes #50

PiperOrigin-RevId: 685752611

java/jsinterop/generator/visitor/DictionaryTypeVisitor.java

@@ -21,16 +21,19 @@
 import static jsinterop.generator.model.PredefinedTypeReference.JS_PROPERTY_MAP;
 import static jsinterop.generator.model.PredefinedTypeReference.OBJECT;
 
+import com.google.common.collect.ImmutableList;
 import jsinterop.generator.model.AbstractVisitor;
 import jsinterop.generator.model.Annotation;
 import jsinterop.generator.model.JavaTypeReference;
 import jsinterop.generator.model.Method;
 import jsinterop.generator.model.MethodInvocation;
 import jsinterop.generator.model.ModelVisitor;
+import jsinterop.generator.model.ParametrizedTypeReference;
 import jsinterop.generator.model.Program;
 import jsinterop.generator.model.ReturnStatement;
 import jsinterop.generator.model.Type;
 import jsinterop.generator.model.TypeQualifier;
+import jsinterop.generator.model.TypeReference;
 
 /**
  * A dictionary type is an interface that contains only JsProperty methods.
@@ -57,8 +60,13 @@ private static void addFactoryMethod(Type type) {
       Method factory = new Method();
       factory.setStatic(true);
       factory.setName("create");
-      factory.setReturnType(new JavaTypeReference(type));
       factory.addAnnotation(Annotation.builder().type(JS_OVERLAY).build());
+      TypeReference returnType = new JavaTypeReference(type);
+      if (!type.getTypeParameters().isEmpty()) {
+        factory.setTypeParameters(ImmutableList.copyOf(type.getTypeParameters()));
+        returnType = new ParametrizedTypeReference(returnType, type.getTypeParameters());
+      }
+      factory.setReturnType(returnType);
       // body statement: return Js.uncheckedCast(JsPropertyMap.of());
       factory.setBody(
           new ReturnStatement(

javatests/jsinterop/generator/externs/generics/RecordWithGeneric.java.txt

@@ -10,7 +10,7 @@ import jsinterop.base.JsPropertyMap;
 @JsType(isNative = true, namespace = JsPackage.GLOBAL)
 public interface RecordWithGeneric<T> {
   @JsOverlay
-  static RecordWithGeneric create() {
+  static <T> RecordWithGeneric<T> create() {
     return Js.uncheckedCast(JsPropertyMap.of());
   }