[LC] Fixed light classes nullability for Kotlin 1.5

Fixed #KT-44472

compiler/testData/asJava/lightClasses/ideRegression/ImplementingMutableSet.java

@@ -2,10 +2,11 @@ public final class SmartSet /* SmartSet*/<T>  extends kotlin.collections.Abstrac
   @org.jetbrains.annotations.NotNull()
   public static final SmartSet.Companion Companion;
 
-  private int size;
-
+  @org.jetbrains.annotations.Nullable()
   private java.lang.Object data;
 
+  private int size;
+
   private static final int ARRAY_THRESHOLD;
 
   @kotlin.jvm.JvmStatic()