Attachment: PDF Link With Valueless Base64 Query Parameter

type.inbound
and any(attachments,
        (.file_type == "pdf" or .file_extension == "pdf")
        and any(file.explode(.),
                any(.scan.pdf.urls,
                    .path == '/'
                    and regex.imatch(.query_params, '[A-Fa-f0-9+/]{8}')
                    and length(.query_params_decoded) == 1
                    and all(flatten(values(.query_params_decoded)), . == '')
                )
        )
)