Server config api operation null check

[kellrott]

Adding check to see if passed api operation is already set before setting it to middleware.NotImplemented
So

api.GetStatusHandler = operations.GetStatusHandlerFunc(func(params operations.GetStatusParams) middleware.Responder {
	return middleware.NotImplemented("operation .GetStatus has not yet been implemented")
})

Becomes

if api.GetStatusHandler == nil {
	api.GetStatusHandler = operations.GetStatusHandlerFunc(func(params operations.GetStatusParams) middleware.Responder {
		return middleware.NotImplemented("operation .GetStatus has not yet been implemented")
	})
}

[codecov]

Codecov Report

Merging #1905 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #1905   +/-   ##
=======================================
  Coverage   80.74%   80.74%           
=======================================
  Files          38       38           
  Lines        7583     7583           
=======================================
  Hits         6123     6123           
  Misses        981      981           
  Partials      479      479

Impacted Files	Coverage Δ
generator/bindata.go	70.92% <100%> (ø)	⬆️

---

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[codecov]

Codecov Report

Merging #1905 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #1905   +/-   ##
=======================================
  Coverage   80.74%   80.74%           
=======================================
  Files          38       38           
  Lines        7583     7583           
=======================================
  Hits         6123     6123           
  Misses        981      981           
  Partials      479      479

Impacted Files	Coverage Δ
generator/bindata.go	70.92% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 873540c...652f232. Read the comment docs.

[kaisawind]

Question on handler set-up #1930