Sort query parameters generated from object

[breezewish]

Describe the PR

Currently swag may generate arbitrary order parameters when parameters come from query & object, like:

type Student struct {
	Name string
	Age int
	Teachers []string
	SkipField map[string]string
}

// @Param request query Student true "query params"

This results in different swagger spec being generated each time even if source code is not modified. Additionally, some openapi client generators like typescript-axios generates each query parameter as function parameters, like:

testGet(age?: number, name?: string, teachers?: Array<string>, options?: any): (axios?: AxiosInstance, basePath?: string) => AxiosPromise<void> {
    ...
}

Thus, unstable parameter order in the specification file will cause code failed to compile at all.

This PR makes parameter order stable by sorting them before output.

Relation issue

Additional context

[sdghchj]

Changes to be done.

[foxluqi]

i think use order tag would be better than field name

[breezewish]

@foxluqi Indeed! However currently the order of the tag is lost after being inserted to the hashmap.. I don't have ideas how to do it.

[codecov-commenter]

Codecov Report

Merging #681 into master will increase coverage by 0.08%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #681      +/-   ##
==========================================
+ Coverage   84.77%   84.85%   +0.08%     
==========================================
  Files           7        7              
  Lines        1859     1869      +10     
==========================================
+ Hits         1576     1586      +10     
  Misses        177      177              
  Partials      106      106              

Impacted Files	Coverage Δ
operation.go	87.79% <100.00%> (+0.21%)	⬆️

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[foxluqi]

@foxluqi Indeed! However currently the order of the tag is lost after being inserted to the hashmap.. I don't have ideas how to do it.

i think the tag information can be read from schema.Properties?

[sdghchj]

@foxluqi @breeswish refer to go-openapi/spec#116 and go-openapi/spec#117