Fix #8936: Correct generic signature for Nothing/Null

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -355,13 +355,11 @@ class Definitions {
   @tu lazy val NothingClass: ClassSymbol = enterCompleteClassSymbol(
     ScalaPackageClass, tpnme.Nothing, AbstractFinal, List(AnyClass.typeRef))
   def NothingType: TypeRef = NothingClass.typeRef
-  @tu lazy val RuntimeNothingModuleRef: TermRef = ctx.requiredModuleRef("scala.runtime.Nothing")
   @tu lazy val NullClass: ClassSymbol = {
     val parent = if (ctx.explicitNulls) AnyType else ObjectType
     enterCompleteClassSymbol(ScalaPackageClass, tpnme.Null, AbstractFinal, parent :: Nil)
   }
   def NullType: TypeRef = NullClass.typeRef
-  @tu lazy val RuntimeNullModuleRef: TermRef = ctx.requiredModuleRef("scala.runtime.Null")
 
   /** An alias for null values that originate in Java code.
    *  This type gets special treatment in the Typer. Specifically, `UncheckedNull` can be selected through:

compiler/src/dotty/tools/dotc/transform/GenericSignatures.scala

@@ -202,9 +202,9 @@ object GenericSignatures {
           else if (sym == defn.UnitClass || sym == defn.BoxedUnitModule)
             jsig(defn.BoxedUnitClass.typeRef)
           else if (sym == defn.NothingClass)
-            jsig(defn.RuntimeNothingModuleRef)
+            builder.append("Lscala/runtime/Nothing$;")
           else if (sym == defn.NullClass)
-            jsig(defn.RuntimeNullModuleRef)
+            builder.append("Lscala/runtime/Null$;")
           else if (sym.isPrimitiveValueClass)
             if (!primitiveOK) jsig(defn.ObjectType)
             else if (sym == defn.UnitClass) jsig(defn.BoxedUnitClass.typeRef)

tests/pos-java-interop/i8936/A.scala

@@ -0,0 +1,3 @@
+class A {
+  def no: List[Nothing] = Nil
+}

tests/pos-java-interop/i8936/B.java

@@ -0,0 +1,8 @@
+import scala.collection.immutable.List;
+
+class B {
+  void Nothingness(){
+    A a = new A();
+    List<scala.runtime.Nothing$> strings = a.no();
+  } 
+}