JMapViewer-1.0-Source.tar.gz is generated by 'get-orig-source' target.

+dfsg1 suffix has been added because bing_maps.png shall be removed at import:
  gbp import-orig --filter bing_maps.png --filter-pristine-tar --pristine-tar -u1.0+dfsg1 \
      ../JMapViewer-1.0-Source.tar.gz

As an alternative, you can use the result of uscan (get-orig-source target),
which is also configured for removal of bing_maps.png (by means of Files-Excluded:
in debian/copyright).