Currently the DocumentInfo property is for export purposes only and meta information about documents is stripped when importing.
According to the PDF specification (ISO 32000), the document info dictionary (often called "metadata" or "Info" dictionary) can include the following standard fields:
• Title: The document’s title.
• Author: The name of the person who created the document.
• Subject: The subject of the document.
• Keywords: Keywords associated with the document.
• Creator: The application that created the original document.
• Producer: The application that converted the document to PDF.
• CreationDate: The date and time the document was created.
• ModDate: The date and time the document was last modified.
• Trapped: Indicates whether the document has been trapped (a printing term).
These fields are stored in the PDF’s Info dictionary and are used by PDF viewers for display, search, and indexing.