use same behaviour for valueOrNull as for valueOrDefault

[robstoll]

• implemented valueOrDefault based on valueOrNull per default
• kept a different implementation for Test/YamlConfig

-fixes #2316

[schalkms]

Execution failed for task ':detekt-generator:verifyGeneratorOutput'.
959> The detekt documentation is not up-to-date. Please build detekt locally to update it and commit the changed files.

[schalkms]

Thanks for tackling that! It looks good to me.

[robstoll]

@schalkms I have updated the documentation. Moreover, I had to change the PR slightly:
ConfigAware and CompositeConfig need to override valueOrDefault due to YamlConfig and TestConfig which implement an additional behaviour in valueOrDefault (LSP violation right in your face 😆).
I don't know the reasons behind the parsing in valueOrDefault and whether this could be moved into Config as well (so that all configs behave the same way) or not.

[codecov-io]

Codecov Report

Merging #2319 into master will decrease coverage by 0.01%.
The diff coverage is 55.55%.

@@             Coverage Diff              @@
##             master    #2319      +/-   ##
============================================
- Coverage     81.87%   81.86%   -0.02%     
  Complexity     2119     2119              
============================================
  Files           348      348              
  Lines          6047     6049       +2     
  Branches       1108     1110       +2     
============================================
+ Hits           4951     4952       +1     
  Misses          512      512              
- Partials        584      585       +1

Impacted Files	Coverage Δ	Complexity Δ
...b/arturbosch/detekt/api/internal/FailFastConfig.kt	36.36% <0%> (ø)	5 <0> (ø)	⬇️
...io/gitlab/arturbosch/detekt/api/CompositeConfig.kt	66.66% <66.66%> (ø)	5 <3> (ø)	⬇️
...n/kotlin/io/gitlab/arturbosch/detekt/api/Config.kt	90% <75%> (-1.67%)	0 <0> (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 f5fd080...127ff3a. Read the comment docs.