Change function signature

src/structure.rs

@@ -1,6 +1,7 @@
-use super::*;
 use crate::color::SeparationInfo;
 
+use super::*;
+
 /// Writer for a _document catalog dictionary_.
 ///
 /// This struct is created by [`Pdf::catalog`].
@@ -136,12 +137,9 @@ impl<'a> Catalog<'a> {
         self.insert(Name(b"OutputIntents")).array().typed()
     }
 
-    /// Start writing the `/AF` array to specify the
-    /// associated files of the document. PDF 2.0+.
-    ///
-    /// Each entry in the array is a reference to a [file specification
-    /// dictionary.](writers::FileSpec)
-    pub fn associated_files(&mut self) -> TypedArray<'_, Ref> {
+    /// Start writing the `/AF` array to specify the associated files of the
+    /// document. PDF 2.0+.
+    pub fn associated_files(&mut self) -> TypedArray<'_, FileSpec> {
         self.insert(Name(b"AF")).array().typed()
     }
 }