Adds types.MismatchedFieldsParams + mismatched_fields_parser.go

[ekartsev]

Notes

When customer attempts to send a request to one of the following Iterable API:

• api/events/track
• api/users/update

and one of the fields in the request has a wrong type,
the Iterable API responds with a 400 status code and the following body:

{
    "msg":"Project xxxx: The request does not have the same data types as the data previously submitted, or the input value is not within the correct range. Field 'my_project_etl:::soc_signup_at' already exists for type 'user' and has a data type of 'date' but possible types 'string, keyword' in the request.",
    "code":"RequestFieldsTypesMismatched",
    "params":{
      "validationErrors":{
        "my_project_etl:::soc_signup_at":{
          "incomingTypes":["string","keyword"],
          "expectedType":"date",
          "category":"user",
          "offendingValue":"2020-04-20 06:12:59.513",
          "_type":"UnexpectedType"
        }
      }
    }    
}

See:

• https://support.iterable.com/hc/en-us/articles/39629320560148-API-Response-Codes#requestfieldstypesmismatched
• https://support.iterable.com/hc/en-us/articles/208183076-Field-Data-Types

NOTE: In the example above the offendingValue does look like a proper date type, but it doesn't follow the formate supported by Iterable, see: https://support.iterable.com/hc/en-us/articles/208183076-Field-Data-Types#date

---

This change adds a way for customers of this client library to get the validationErrors from the RequestFieldsTypesMismatched responses.

Tests

• new unit tests