Fixed JSON issue with Multiline API Description

[lonnblad]

Describe the PR
Fixed an issue where the JSON breaks when programmatically setting a Multiline API Description.

Relation issue
#480

[codecov-io]

Codecov Report

Merging #481 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #481   +/-   ##
=======================================
  Coverage   86.58%   86.58%           
=======================================
  Files           7        7           
  Lines        1558     1558           
=======================================
  Hits         1349     1349           
  Misses        120      120           
  Partials       89       89

Impacted Files	Coverage Δ
gen/gen.go	89.65% <ø> (ø)	⬆️

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[ubogdan]

please replace strings.ReplaceAll with strings.Replace .

Replace all was introduced in go 1.12 and will break compatibility with older go versions.

[ubogdan]

LGTM