Update pdfa_cc_main_2021_31_pdf_untruncated.py

pdfa_cc_main_2021_31_pdf_untruncated.py

@@ -50,6 +50,7 @@ _MISSING_PDFS = {
     "7889525.pdf"
 }
 
+
 class Pdfa(datasets.GeneratorBasedBuilder):
 
     def _info(self):
@@ -147,7 +148,7 @@ class Pdfa(datasets.GeneratorBasedBuilder):
                         "pdf_bytes": pdf_file.read(),
                         "file_name": file_name,
                         "url_id": url_id,
-                        "cc_host": cc_host_dict,
-                        "cc_provenance": cc_provenance_dict,
-                        "pdfinfo": pdfinfo_dict
+                        "cc_host": {k: v if v else None for k, v in cc_host_dict.items()},
+                        "cc_provenance": {k: v if v else None for k, v in cc_provenance_dict.items()},
+                        "pdfinfo": {k: v if v else None for k, v in pdfinfo_dict.items()}
                     }