Validate method modifies the input 'api' param inplace

The following code alters the contents of inputAPIDoc:

var SwaggerParser = require('swagger-parser');
var inputAPIDoc = {
    "swagger": "2.0",
    "info": {
        "version": "0.0.0",
        "title": "Simple API"
    },
    "paths": {
        "/": {
            "get": {
                "responses": {
                    "200": {
                        "description": "OK",
                        "schema": {
                            "$ref": "#/definitions/ScoredTopic"
                        }
                    },
                    "400": {
                        "description": "bad request",
                        "schema": {
                            "$ref": "#/definitions/badreq"
                        }
                    }
                }
            }
        }
    },
    "definitions": {
        "ScoredTopic": {
            "properties": {
                "topics": {
                    "type": "array",
                    "items": {
                        "$ref": "#/definitions/ScoredTopic"
                    }
                }
            }
        },
        "badreq": {
            "properties": {
                "topics": {
                    "type": "string",
                    "description": "details on why the error occured"
                }
            }
        }
    }

}
console.log(JSON.stringify(inputAPIDoc));
SwaggerParser.validate(inputAPIDoc, { dereference: { circular: false } }, function (err, api) {
    console.log("--------------------------");
    console.log(JSON.stringify(inputAPIDoc));
    if (err) {
        if (err.name === "ReferenceError" && err.message === "The API contains circular references") {
            console.log(err.message);
        }
        else {
            console.log(err);
        }
    }
    else {
        console.log("success");
    }
});

setTimeout(function () {
    console.log("**************************");
    console.log(JSON.stringify(inputAPIDoc));
}, 2000);

Output of the above code:

{"swagger":"2.0","info":{"version":"0.0.0","title":"Simple API"},"paths":{"/":{"get":{"responses":{"200":{"description":"OK","schema":{"$ref":"#/definitions/ScoredTopic"}},"400":{"description":"bad request","schema":{"$ref":"#/definitions/badreq"}}}}}},"definitions":{"ScoredTopic":{"properties":{"topics":{"type":"array","items":{"$ref":"#/definitions/ScoredTopic"}}}},"badreq":{"properties":{"topics":{"type":"string","description":"details on why the error occured"}}}}}
--------------------------
{"swagger":"2.0","info":{"version":"0.0.0","title":"Simple API"},"paths":{"/":{"get":{"responses":{"200":{"description":"OK","schema":{"$ref":"#/definitions/ScoredTopic"}},"400":{"description":"bad request","schema":{"properties":{"topics":{"type":"string","description":"details on why the error occured"}}}}}}}},"definitions":{"ScoredTopic":{"properties":{"topics":{"type":"array","items":{"$ref":"#/definitions/ScoredTopic"}}}},"badreq":{"properties":{"topics":{"type":"string","description":"details on why the error occured"}}}}}
The API contains circular references
**************************
{"swagger":"2.0","info":{"version":"0.0.0","title":"Simple API"},"paths":{"/":{"get":{"responses":{"200":{"description":"OK","schema":{"$ref":"#/definitions/ScoredTopic"}},"400":{"description":"bad request","schema":{"properties":{"topics":{"type":"string","description":"details on why the error occured"}}}}}}}},"definitions":{"ScoredTopic":{"properties":{"topics":{"type":"array","items":{"$ref":"#/definitions/ScoredTopic"}}}},"badreq":{"properties":{"topics":{"type":"string","description":"details on why the error occured"}}}}}

As we can see, the value of the var inputAPIDoc is altered on return from the validate call.
API documentation does not talk about this. Hence would be better if the same is clarified

Start by reviewing the SwaggerParser.validate API documentation and its handling of the input API object, as shown in the issue example. Document whether validation may modify the supplied object, including the observed dereferencing behavior, and ensure the documented behavior matches the implementation.