Filter duplicate co-authors from SpaceDock

[HebaruSan]

Problem

This mod:

https://spacedock.info/mod/2992/SRB%20Waterfall%20Effects%20(SWE)

... gave me this inflation error locally after fixing the install to match the latest download:

Schema validation failed: #/author: NotOneOf

Cause

The co-author was added twice:

... which we simply dumped into a List<string>, but it's not allowed in the schema (note uniqueItems):

CKAN/CKAN.schema

Lines 47 to 57 in 4f3da57

	"author" : {
	"description" : "Author, or list of authors",
	"oneOf" : [
	{ "type" : "string" },
	{
	"type" : "array",
	"items" : { "type" : "string" },
	"uniqueItems" : true
	}
	]
	},

Since neither the simple string format nor the unique-array format matched, the validator considered the oneOf to be the thing that failed.

Changes

Now the SpaceDock translator ensures co-author uniqueness with .Distinct(). Initially I looked at using a HashSet, but then we would lose the ordering of the authors. I wanted to avoid generating more temporary values, and since you can't add yourself as a co-author, this seemed sufficient to cover the problematic cases.

I audited the GitHub translator and as far as I can tell it already ensures uniqueness with .Contains() calls. I don't think any of the other translators can generate multiple authors.

This should probably also be fixed on the SpaceDock side at some point, but it's good to satisfy constraints in the same project that imposes them.

[techman83]

Yep, that looks to be a sensible approach.