Replaced InvalidGridException with a logger warning

[avgprog]

Resolves #148. Changes done -

• Replaced InvalidGridException with a logger warning in case a JointGridContainer only consists of a single SubGridContainer.

[codecov]

Codecov Report

Merging #278 (1eb680e) into dev (bf2b182) will increase coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                dev     #278      +/-   ##
============================================
+ Coverage     78.25%   78.29%   +0.04%     
- Complexity     1947     1950       +3     
============================================
  Files           247      247              
  Lines          7910     7911       +1     
  Branches        747      747              
============================================
+ Hits           6190     6194       +4     
+ Misses         1301     1299       -2     
+ Partials        419      418       -1     

Impacted Files	Coverage Δ	Complexity Δ
...del/models/input/container/JointGridContainer.java	76.19% <0.00%> (+16.19%)	7.00% <0.00%> (+3.00%)

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[avgprog]

Since, the code coverage test is failing, I suppose I need to add some test cases to check the newly added changes.

[ckittl]

Your test actually does only add limited value. Ideally, you would also test, that the log call has been made. However, in our case it is not easy to do.

It would work, if you would have the logger non-static and non-final. Then you could replace it with a mock or a spy on a delegate. However, completeness of the test doesn't justify design changes with given drawbacks.