XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20190331.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20190331.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20190331_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20190331_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20190331_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20190331_def.xml -

XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20181231.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20181231.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20181231_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20181231_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20181231_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20181231_def.xml -

XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20180930.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20180930.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20180930_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20180930_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20180930_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20180930_def.xml -

XBRL Item – Ex-101.INS-XBRL Instance Document - nick-20180630.xml -

XBRL Item – Ex-101.SCH-XBRL Taxonomy Extension Schema Document - nick-20180630.xsd -

XBRL Item – Ex-101.CAL-XBRL Taxonomy Extension Calculation Linkbase Document - nick-20180630_cal.xml -

XBRL Item – Ex-101.LAB-XBRL Taxonomy Extension Label Linkbase Document - nick-20180630_lab.xml -

XBRL Item – Ex-101.PRE-XBRL Taxonomy Extension Presentation Linkbase Document - nick-20180630_pre.xml -

XBRL Item – Ex-101.DEF-XBRL Taxonomy Extension Definition Linkbase Document - nick-20180630_def.xml -