Fixed MappingConverter when methods are null

[StefH]

No description provided.

[codecov]

Codecov Report

Merging #487 into master will increase coverage by 0.13%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #487      +/-   ##
==========================================
+ Coverage   75.84%   75.98%   +0.13%     
==========================================
  Files         136      136              
  Lines        5130     5130              
  Branches      504      504              
==========================================
+ Hits         3891     3898       +7     
+ Misses       1092     1084       -8     
- Partials      147      148       +1     

Impacted Files	Coverage Δ
src/WireMock.Net/Serialization/MappingConverter.cs	51.49% <100.00%> (ø)
src/WireMock.Net/Server/WireMockServer.Admin.cs	56.86% <0.00%> (+0.90%)	⬆️
...eMock.Net.Abstractions/Admin/Mappings/BodyModel.cs	100.00% <0.00%> (+50.00%)	⬆️

---

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 28865bd...af42d32. Read the comment docs.