Set TypeVariable isNullable if the type variable is explicitly marked…

… as Nullable in the Koltin code.

With this change we follow what we do in the JDT frontend.
TypeVariable can be used as JsOptional parameter as they can be marked as nullable.

PiperOrigin-RevId: 591141777

transpiler/javatests/com/google/j2cl/readable/java/nullability/defaultnotnullable/DefaultNotNullable.java

@@ -20,6 +20,7 @@
 import javax.annotation.Nonnull;
 import jsinterop.annotations.JsMethod;
 import jsinterop.annotations.JsNonNull;
+import jsinterop.annotations.JsOptional;
 import org.jspecify.nullness.Nullable;
 
 public class DefaultNotNullable {
@@ -57,6 +58,11 @@ public String m2(@Nullable String a, List<@Nullable Double> b) {
   public void m3(String... args) {
   }
 
+  @JsMethod
+  public String m4(String a, @JsOptional @Nullable String optional) {
+    return null;
+  }
+
   interface ParameterizedInterface<T> {
     // Exposes the problems described in b/68726480.
     T add(T t);
@@ -124,6 +130,9 @@ void setNullable(@Nullable N n) {}
     void setNonNull(@JsNonNull N n) {}
 
     void setDefaultNullability(N n) {}
+
+    @JsMethod
+    void jsOptional(String a, @JsOptional @Nullable N optional) {}
   }
 
   static class ParameterizedNullable<N extends @Nullable Object> {

transpiler/javatests/com/google/j2cl/readable/java/nullability/output_closure/defaultnotnullable/DefaultNotNullable$ParameterizedDefaultNullability.impl.java.js.txt

@@ -51,6 +51,8 @@ class ParameterizedDefaultNullability extends j_l_Object {
  m_setNonNull__java_lang_Object__void_$pp_nullability_defaultnotnullable(/** N */ n) {}
  /** @nodts */
  m_setDefaultNullability__java_lang_Object__void_$pp_nullability_defaultnotnullable(/** N */ n) {}
+
+ jsOptional(/** string */ a, /** N= */ optional) {}
  /** @nodts */
  static $clinit() {
   ParameterizedDefaultNullability.$clinit = () =>{};

transpiler/javatests/com/google/j2cl/readable/java/nullability/output_closure/defaultnotnullable/DefaultNotNullable$ParameterizedDefaultNullability.js.mappings.txt

@@ -36,6 +36,9 @@
 [n] => [n] "n"
 [setDefaultNullability] => [m_setDefaultNullability__java_lang_Object__void_$pp_nullability_defaultnotnullable]
 [n] => [n] "n"
+[jsOptional] => [jsOptional]
+[a] => [a] "a"
+[optional] => [optional] "optional"
 [ParameterizedDefaultNullability] => [$clinit]
 [ParameterizedDefaultNullability] => [ParameterizedDefaultNullability.$clinit = () =>{};] "nullability.defaultnotnullable.DefaultNotNullable$ParameterizedDefaultNullability.<clinit>"
 [ParameterizedDefaultNullability] => [ParameterizedDefaultNullability.$loadModules();] "nullability.defaultnotnullable.DefaultNotNullable$ParameterizedDefaultNullability.<clinit>"

transpiler/javatests/com/google/j2cl/readable/java/nullability/output_closure/defaultnotnullable/DefaultNotNullable.impl.java.js.txt

@@ -72,6 +72,10 @@ class DefaultNotNullable extends j_l_Object {
  m3(.../** ...string */ args) {
   $Arrays.$stampType(args, j_l_String, 1);
  }
+ /** @return {string} */
+ m4(/** string */ a, /** ?string= */ optional) {
+  return null;
+ }
  /** @nodts @template T */
  m_methodWithNullableBound__void_$pp_nullability_defaultnotnullable() {}
  /** @nodts @template T */

transpiler/javatests/com/google/j2cl/readable/java/nullability/output_closure/defaultnotnullable/DefaultNotNullable.js.mappings.txt

@@ -68,6 +68,10 @@
 [args] => [args] "args"
 [{
   }] => [$Arrays.$stampType(args, j_l_String, 1);] "nullability.defaultnotnullable.DefaultNotNullable.m3"
+[m4] => [m4]
+[a] => [a] "a"
+[optional] => [optional] "optional"
+[return null;] => [return null;] "nullability.defaultnotnullable.DefaultNotNullable.m4"
 [methodWithNullableBound] => [m_methodWithNullableBound__void_$pp_nullability_defaultnotnullable]
 [methodWithNonNullableBound] => [m_methodWithNonNullableBound__void_$pp_nullability_defaultnotnullable]
 [genericNullableMethod] => [m_genericNullableMethod__nullability_defaultnotnullable_DefaultNotNullable_ParameterizedNullable__java_lang_Object__void]

transpiler/javatests/com/google/j2cl/readable/java/nullability/output_kt/defaultnotnullable/DefaultNotNullable.kt.txt

@@ -22,6 +22,7 @@ import java.lang.RuntimeException
 import java.lang.Void
 import java.util.ArrayList
 import jsinterop.annotations.JsMethod
+import jsinterop.annotations.JsOptional
 import kotlin.Any
 import kotlin.Array
 import kotlin.Boolean
@@ -108,6 +109,15 @@ open class DefaultNotNullable {
   val args_1: Array<String> = args as Array<String>
  }
 
+ @ObjCName("m4")
+ @JsMethod
+ open fun m4(
+  @ObjCName("withNSString") a: String,
+  @ObjCName("withNSString") @JsOptional optional: String?
+ ): String {
+  return null!!
+ }
+
  internal open fun <T: DefaultNotNullable.NullableBound<T>?> methodWithNullableBound_pp_nullability_defaultnotnullable() {}
 
  internal open fun <T: DefaultNotNullable.NonNullableBound<T>> methodWithNonNullableBound_pp_nullability_defaultnotnullable() {}
@@ -392,6 +402,9 @@ open class DefaultNotNullable {
   internal open fun setNonNull_pp_nullability_defaultnotnullable(n: N) {}
 
   internal open fun setDefaultNullability_pp_nullability_defaultnotnullable(n: N) {}
+
+  @JsMethod(name = "jsOptional")
+  internal open fun jsOptional_pp_nullability_defaultnotnullable(a: String, @JsOptional optional: N?) {}
  }
 
  open class ParameterizedNullable<N> {