Attachment: 8-K


hfc-20210512.xsd
Attachment: XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT


hfc-20210512_cal.xml
Attachment: XBRL TAXONOMY EXTENSION CALCULATION LINKBASE DOCUMENT


hfc-20210512_def.xml
Attachment: XBRL TAXONOMY EXTENSION DEFINITION LINKBASE DOCUMENT


hfc-20210512_lab.xml
Attachment: XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT


hfc-20210512_pre.xml
Attachment: XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT