Fixes issue of Method normalize with return type '' is different to return type 'ArrayObject|array<array-key, mixed>|null|scalar' of inherited method NormalizerInterface::normalize

[kedarkhaire]

Fixes #383

[codecov]

Codecov Report

Attention: Patch coverage is 91.66667% with 3 lines in your changes missing coverage. Please review.

Project coverage is 86.68%. Comparing base (d90650c) to head (df6f2a1).

Files with missing lines	Patch %	Lines
.../Api/ApigeeX/Normalizer/RatePlanRateNormalizer.php	0.00%	1 Missing ⚠️
...rmalizer/LegalEntityReportDefinitionNormalizer.php	0.00%	1 Missing ⚠️
src/Normalizer/CredentialProductNormalizer.php	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##                4.x     #390   +/-   ##
=========================================
  Coverage     86.68%   86.68%           
  Complexity     1737     1737           
=========================================
  Files           343      343           
  Lines          4220     4220           
=========================================
  Hits           3658     3658           
  Misses          562      562           

Flag	Coverage Δ
unittests	86.68% <91.66%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
.../ApigeeX/Normalizer/AcceptedRatePlanNormalizer.php	100.00% <100.00%> (ø)
...rc/Api/ApigeeX/Normalizer/ApiProductNormalizer.php	100.00% <100.00%> (ø)
...pigeeX/Normalizer/AppGroupMembershipNormalizer.php	100.00% <100.00%> (ø)
src/Api/ApigeeX/Normalizer/AppNormalizer.php	100.00% <100.00%> (ø)
...c/Api/ApigeeX/Normalizer/BillingTypeNormalizer.php	100.00% <100.00%> (ø)
src/Api/ApigeeX/Normalizer/RatePlanNormalizer.php	70.00% <100.00%> (ø)
...i/ApigeeX/Normalizer/RatePlanNormalizerFactory.php	100.00% <100.00%> (ø)
.../ApigeeX/Normalizer/StandardRatePlanNormalizer.php	100.00% <100.00%> (ø)
.../Management/Normalizer/AppCredentialNormalizer.php	100.00% <100.00%> (ø)
src/Api/Management/Normalizer/AppNormalizer.php	100.00% <100.00%> (ø)
... and 26 more