src/Pure/Thy/document_build.scala

     def session: String = info.name
     def options: Options = info.options
 
     override def toString: String = session
 
-    val classpath: List[File.Content_Bytes] = session_context.classpath()
+    val classpath: List[File.Content] = session_context.classpath()
 
     def document_bibliography: Boolean = options.bool("document_bibliography")
 
     def document_logo: Option[String] =
       options.string("document_logo") match {