Order and trade experimental contexts

[kriswest]

resolves #644
resolves #655

Experimental Order and Trade types, as discussed at Standards Working Group #1013 and Context Data & Intents #1019.

Implemented with documentation in the schema (to save adding it later when we add to all types). Markdown documentation to come. In the course of doing so, we discovered that docs should not be added for pure reference fields (it should be a description on the reference itself, and common to all usages of that reference).

These types seemed to imply a Product type, which has also been added as part of this PR.

Examples:

• Order

  {
      "type": "fdc3.order",
      "name": "...",
      "id": {
    	  "myOMS": "12345"
      },
      "details": {
    	  "product": {
    		  "type": "fdc3.product",
    		  "instrument": {
    			  "type": "fdc3.instrument",
    			  "id": {
    				  "ticker": "MSFT"
    			  }
    		  }
    	  }
      }
  }

  {
      "type": "fdc3.order",
      "id": {
    	  "myOMS": "ABC123"
      }
  }

• Trade

  {
      "type": "fdc3.trade",
      "name": "...",
      "id": {
    	  "myEMS": "12345"
      },
      "product": {
    	  "type": "fdc3.product",
    	  "instrument": {
    		  "type": "fdc3.instrument",
    		  "id": {
    			  "ticker": "MSFT"
    		  }
    	  }
      }
  }

• Product

  {
      "type": "fdc3.product",
      "instrument": {
    	  "type": "fdc3.instrument",
    	  "id": {
    		  "ticker": "MSFT"
    	  }
      }
  }

Note the nesting of the product in order under a details object (not itself a context). I figured that, if (as discussed) an order can have no product, then it might accumulate other details fields, which it would make sense to keep together. Trade, which requires a product, does not do this.

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[kriswest]

@nemery @hampshanubs @dominicgifford Here are those draft contexts for your review. Examples in the PR, schemas to read in the files tab. I'll add the markdown docs this week after you've had a first look (in case you see immediate changes needed).

Let me know how these look ASAP please.

[mistryvinay]

LGTM

[timjenkel]

You probably discussed this in one of the meetings, but what is the difference between Instrument and Product?

[kriswest]

You probably discussed this in one of the meetings, but what is the difference between Instrument and Product?

@timjenkel A tradeable product might be an instrument, but it also might be a cash raise, a swap or something else. Hence, we created a product type as a place to put more detail as needed (I'm no expert but @dominicgifford, @nemery and @hampshanubs are and thought it made sense).

You can see the current @experimental and extensible definition at: https://fdc3.finos.org/docs/next/context/ref/Product and how its used at https://fdc3.finos.org/docs/next/context/ref/Order and https://fdc3.finos.org/docs/next/context/ref/Trade. Feedback and further discussion are (as always) most welcome