Preserve examples

[dschulten]

What's this PR do/fix?

This PR ensures that Examples added with ApiResponse annotations are no longer dropped when merging ResponseMessages in OperationBuilder.

Are there unit tests? If not how should this be manually tested?

OperationBuilderSpec
def "Response message builder is non-destructive"

Any background context you want to provide?

I need examples to add response example snippets created by spring-restdocs in spring-integration for springfox

What are the relevant issues?

None

[codecov]

Codecov Report

Merging #2778 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master    #2778      +/-   ##
============================================
+ Coverage     94.77%   94.78%   +<.01%     
  Complexity     3161     3161              
============================================
  Files           354      354              
  Lines          8057     8067      +10     
  Branches        608      608              
============================================
+ Hits           7636     7646      +10     
  Misses          271      271              
  Partials        150      150

Impacted Files	Coverage Δ	Complexity Δ
...ngfox/documentation/builders/OperationBuilder.java	100% <100%> (ø)	26 <0> (ø)	⬇️

[dilipkrish]

Thank you @dschulten for catching that!