XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20210331.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20210331.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20210331_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20210331_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20210331_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20210331_def.xml -

XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20201231.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-202001231xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20201231_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20201231_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20201231_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20201231_def.xml -

XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20200930.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20200930.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20200930_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20200930_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20200930_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20200930_def.xml -

XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20200630.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20200630.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20200630_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20200630_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20200630_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20200630_def.xml -