ListResponse not paginating as expected

[sleelin]

Currently, ListResponse will paginate the results only when the length of the supplied resources array is greater than the supplied itemsPerPage value, which defaults to 20. This process does not take into account a supplied startIndex, meaning more results will be included in a page than expected when totalResults is less than itemsPerPage, effectively ignoring startIndex.

Steps to reproduce: Instantiate a new ListResponse with a specified startIndex and fewer resources than itemsPerPage

new ListResponse(new Array(11).fill({}).map((_, i) => ({index: i+1})), {startIndex: 10, itemsPerPage: 11});

Expected behaviour: Resources in the ListResponse should begin from the supplied startIndex

ListResponse {
  schemas: [ 'urn:ietf:params:scim:api:messages:2.0:ListResponse' ],
  totalResults: 11,
  Resources: [
    { index: 11 }
  ],
  startIndex: 10,
  itemsPerPage: 20
}

Actual behaviour: All resources are included in the ListResponse, and startIndex is ignored

ListResponse {
  schemas: [ 'urn:ietf:params:scim:api:messages:2.0:ListResponse' ],
  totalResults: 11,
  Resources: [
    { index: 1 },  { index: 2 },
    { index: 3 },  { index: 4 },
    { index: 5 },  { index: 6 },
    { index: 7 },  { index: 8 },
    { index: 9 },  { index: 10 },
    { index: 11 }
  ],
  startIndex: 10,
  itemsPerPage: 20
}