XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20200331.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20200331.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20200331_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20200331_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20200331_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20200331_def.xml -

XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20191231.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20191231.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20191231_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20191231_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20191231_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20191231_def.xml -

XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20190930.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20190930.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20190930_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20190930_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20190930_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20190930_def.xml -

XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20190630.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20190630.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20190630_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20190630_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20190630_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20190630_def.xml -