For a given var declaration in the constructor, the compiler will create the getters and setters automatically. Considering the title field, the compiler has actually created a getTitle and setTitle method. This means interacting with Java would now translate to calling these two methods:

public final java.lang.String getTitle();
Code:
0: aload_0
1: getfield      #11                 // Field title:Ljava/lang/String;
4: areturn
public final void setTitle(java.lang.String);
Code:
0: aload_1
1: ldc           #17                 // String <set-?>
3: invokestatic  #23                 // Method kotlin/jvm/internal/Intrinsics.checkParameterIsNotNull:(Ljava/lang/Object;Ljava/lang/String;)V
6: aload_0
7: aload_1
8: putfield      #11                 // Field title:Ljava/lang/String;
11: return

The code is pretty straightforward. In the setter code body, see line 3, we have an implicit check for null values via the standard library method, checkParameterIsNotNull...