Made some args optional.

[siad007]

Related to #1034

[codecov]

Codecov Report

Merging #1058 into master will decrease coverage by <.01%.
The diff coverage is 63.63%.

@@             Coverage Diff              @@
##             master    #1058      +/-   ##
============================================
- Coverage     46.65%   46.65%   -0.01%     
- Complexity    10029    10032       +3     
============================================
  Files           505      505              
  Lines         24457    24464       +7     
============================================
+ Hits          11410    11413       +3     
- Misses        13047    13051       +4

Impacted Files	Coverage Δ	Complexity Δ
classes/phing/types/AbstractFileSet.php	71.79% <63.63%> (-1.08%)	89 <21> (+3)

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