Potentially confusing use of [string] and other single-value type arrays in schema reference & FLMT

[pindec]

In some places in the schema reference, we have both [string] and string listed as types, which mean the same thing, and are distinct from array[string].

Examples:

• currency e.g. finalValue/currency | [string]
• Organization name e.g. tender/tenderers/0/name | [string]
• dates e.g. contractPeriod/startDate | [string]

It seems when these items are copied from the OCDS schema, and the null option is removed from the type array, only one option is left in that array, [string].

They also appear slightly differently in the FLMT:

additionalClassifications/scheme	['string']	Scheme
additionalClassifications/id	string	ID

And affects other types:

• amount | [number]
• durationInDays | [integer]

This is potentially confusing, and is likely the source of some questions about cardinality of objects in the OC4IDS schema we've had recently.

We should check for situations where only one value is in the type array and adjust it to that value only.

[duncandewhurst]

This should be an easy fix in borrow_schema.py

[duncandewhurst]

Moving to iterative improvements since this change would result in no change to meaning or behavior.