Generate example for nullable and empty string props

[Ivan-Baranov]

In schema (json body)

            area:
              type: string
              nullable: true
              example: null
            area_type:
              type: string
              nullable: true
              example: ''

In example field:

      "area": "string",
      "area_type": "string",

Expecting:

      "area": null,
      "area_type": "",

[mrin9]

will look into this

[abrari]

I think that there is a regression on this issue. After debugging it locally, I found in this code:

export function getSampleValueByType(schemaObj) {
  const example = schemaObj.examples
    ? schemaObj.examples[0]
    : schemaObj.example
      ? schemaObj.example
      : undefined;

example goes undefined if schemaObj.example is null.