Specializing a method on a value class

ImplicitTest.scala

import scala.{specialized => spec}

package object foo {
  class ImplicitTest(val n: Nothing) extends AnyVal {
    def foo[@spec(Double) T](size: Int)(f: Int => T): Array[T] = {
      f(42)
      ???
    }
  }
}

javap

public class foo.package$ImplicitTest$ {
  public static foo.package$ImplicitTest$ MODULE$;

  public static {};
    Code:
       0: new           #2                  // class foo/package$ImplicitTest$
       3: invokespecial #18                 // Method "<init>":()V
       6: return

  public final <T> java.lang.Object foo$extension(scala.runtime.Nothing$, int, scala.Function1<java.lang.Object, T>);
    Code:
       0: aload_3
       1: bipush        42
       3: invokestatic  #29                 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer;
       6: invokeinterface #35,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
      11: pop
      12: getstatic     #40                 // Field scala/Predef$.MODULE$:Lscala/Predef$;
      15: invokevirtual #44                 // Method scala/Predef$.$qmark$qmark$qmark:()Lscala/runtime/Nothing$;
      18: athrow
  ...
}

public final class foo.package$ImplicitTest {
  public scala.runtime.Nothing$ n();
    Code:
       0: aload_0
       1: getfield      #16                 // Field n:Lscala/runtime/Nothing$;
       4: areturn

  public <T> java.lang.Object foo(int, scala.Function1<java.lang.Object, T>);
    Code:
       0: getstatic     #26                 // Field foo/package$ImplicitTest$.MODULE$:Lfoo/package$ImplicitTest$;
       3: aload_0
       4: invokevirtual #28                 // Method n:()Lscala/runtime/Nothing$;
       7: iload_1
       8: aload_2
       9: invokevirtual #32                 // Method foo/package$ImplicitTest$.foo$extension:(Lscala/runtime/Nothing$;ILscala/Function1;)Ljava/lang/Object;
      12: areturn
  ...
}