Create a FormParameter model object instead of BodyParameter

[shartte]

This fixes #2717 by creating the right Swagger model class for parameters of type "formData".
Since those parameters only support a single example, I've also opted to simply copy over the first one.

[shartte]

I've adapted the class so that it only maps to FormParameter now if the type is one of the types supported by the spec. In other cases it falls back to BodyParameter, which is seemingly wrong, but matches previous behavior better.
I've also added a few unit tests for these cases.
Since the "spec" tests don't run on my own machine, I hope my adapted tests data will work on the CI.

[Carmageddon]

Whats up with this PR? Can you please get it fixed so we would not have to build based on your repo on Monday :)

[dilipkrish]

@shartte thanks for the PR. It appears that the contract tests are failing. Would you mind taking a look?

[shartte]

@dilipkrish Will do, I had some issues with getting them to run initially, but now they work for me. So I'll investigate.

[codecov]

Codecov Report

Merging #2722 into master will decrease coverage by 0.05%.
The diff coverage is 76.92%.

@@             Coverage Diff              @@
##             master    #2722      +/-   ##
============================================
- Coverage     94.77%   94.71%   -0.06%     
- Complexity     3161     3166       +5     
============================================
  Files           354      354              
  Lines          8057     8081      +24     
  Branches        608      612       +4     
============================================
+ Hits           7636     7654      +18     
- Misses          271      276       +5     
- Partials        150      151       +1

Impacted Files	Coverage Δ	Complexity Δ
...ocumentation/swagger2/mappers/ParameterMapper.java	84.5% <76.92%> (-4.86%)	15 <7> (+5)

[kremers]

Having issues with #2717
Very happy with the solution, hope it makes it in 3.0.0-SNAPSHOT soon