Import Data for Group Calendar (Classic)

lightweight tag d8b336deffccd43b033a7799035021c0c792ab45 v1.0.1
Author:    lantisnt <lantisnt@github.com>
Date:    Tue Feb 4 23:18:03 2020 +0100

commit d8b336deffccd43b033a7799035021c0c792ab45
Author: lantisnt <lantisnt@github.com>
Date:   Tue Feb 4 23:18:03 2020 +0100

    Added examples and fixes

commit 5679ddd19858d06636052f4f27780a2a511bdf95
Author: lantisnt <lantisnt@github.com>
Date:   Tue Feb 4 22:33:52 2020 +0100

    Fix unknown class handling

commit 826c3fa54a5dba55dac3ed98d1c17eda728d9486
Author: lantisnt <lantisnt@github.com>
Date:   Tue Feb 4 22:28:53 2020 +0100

    Add handling no attnedees

commit 5b14bf55dd7a8d02189f69b4e669777e0aaf8b1f
Author: lantisnt <lantisnt@github.com>
Date:   Tue Feb 4 22:23:35 2020 +0100

    Add required column validation