[BUG] Java codegen generates incorrect example for collections of objects in ApiModelProperty annotation

For the following sample model:

{

  "swagger": "2.0",
  "definitions": {
    "sampleDef": {
      "type": "object",e
      "properties": {
        "type": {
          "type": "string"
        },
        "value": {
          "type": "string"
        }
      }
    },
    "account": {
      "type": "object",
      "properties": {
        "samples": {
          "type": "array",
          "items": {
            "$ref": "#/definitions/sampleDef"
          },
          "example": [
            {
              "type": "sample",
              "value": "some value"
            }
          ]
        }
      }
    }
  }

the generated annotation is:

@ApiModelProperty(example = "[{type=sample, value=some value}]", value = "")

which leads to a malformed json (swagger.json generated by, for example, Springfox), for example:

JSON:

{
   "type":"array",
   "example":[
      {
         type=sample,
         value=some value
      }
   ],
   "items":{
      "$ref":"#/definitions/sampleDef"
   }
}

YAML:

      samples:
        type: array
        example:
          - type=sample: null
            value=some value: null

I think it the correct example should be:

@ApiModelProperty(example = "[{type: sample, value: some value}]", value = "")

which would give

  samples:
    type: array
    example:
      - type: sample
        value: some value

I believe the issue exists in toExampleValue method in DefaultCodegen class which simply calls toString method on an object returned by schema.getExample() which in this case is java.util.ArrayList instance containing one java.util.LinkedHashMap object, which contains two key value pairs:

"type" -> "sample"
"value" -> "some value"

Using json serialization instead of toString could be a solution. Serializing would give

[{"type":"sample","value":"some value"}]

instead of

[{type=sample, value=some value}]

Start with the toExampleValue method in the DefaultCodegen class and reproduce the supplied Swagger 2.0 model. Inspect the generated ApiModelProperty example for the collection of objects; done means the example preserves valid JSON object syntax instead of Java collection and map toString output.