Juniper: don't try to generate transformations without an interface IP

[anothermattbrown]

This prevents NPE when an interface has no IP.

[batfish-bot]

This change is 

[codecov]

Codecov Report

Merging #3343 into master will decrease coverage by <.01%.
The diff coverage is 50%.

@@             Coverage Diff              @@
##             master    #3343      +/-   ##
============================================
- Coverage     72.87%   72.87%   -0.01%     
+ Complexity    23339    23311      -28     
============================================
  Files          2031     2028       -3     
  Lines         98063    97995      -68     
  Branches      11724    11714      -10     
============================================
- Hits          71465    71409      -56     
+ Misses        21382    21380       -2     
+ Partials       5216     5206      -10

Impacted Files	Coverage Δ	Complexity Δ
...h/representation/juniper/JuniperConfiguration.java	88.89% <50%> (-0.43%)	361 <0> (+1)
...ipsecsessionstatus/IpsecSessionStatusQuestion.java	70.58% <0%> (-15.13%)	6% <0%> (ø)
...specifier/InterfaceNameRegexLocationSpecifier.java	53.33% <0%> (-13.34%)	4% <0%> (-1%)
...tfish/specifier/VrfNameRegexLocationSpecifier.java	53.33% <0%> (-13.34%)	4% <0%> (-1%)
...er/InterfaceDescriptionRegexLocationSpecifier.java	53.33% <0%> (-13.34%)	4% <0%> (-1%)
...rg/batfish/datamodel/questions/NodesSpecifier.java	71.31% <0%> (-7.38%)	37% <0%> (-2%)
...rc/main/java/org/batfish/datamodel/flow/Trace.java	73.33% <0%> (-6.67%)	8% <0%> (-1%)
...on/traceroute/BidirectionalTracerouteAnswerer.java	61.6% <0%> (-1.79%)	13% <0%> (ø)
...ipsecsessionstatus/IpsecSessionStatusAnswerer.java	57.77% <0%> (-0.65%)	12% <0%> (ø)
...ava/org/batfish/question/ReachabilitySettings.java	46.21% <0%> (-0.41%)	4% <0%> (ø)
... and 18 more

[arifogel]

Reviewed 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved

[arifogel]

Reviewable status: complete! all files reviewed, all discussions resolved