While Compiling the tzdata2016a the below NPE is thrown:
java.lang.NullPointerException
                at build.tools.tzdb.ZoneRules.writeRule(ZoneRules.java:235)
                at build.tools.tzdb.ZoneRules.writeExternal(ZoneRules.java:186)
                at build.tools.tzdb.TzdbZoneRulesCompiler.outputFile(TzdbZoneRulesCompiler.java:266)
                at build.tools.tzdb.TzdbZoneRulesCompiler.compile(TzdbZoneRulesCompiler.java:217)
                at build.tools.tzdb.TzdbZoneRulesCompiler.main(TzdbZoneRulesCompiler.java:89)
 
It fails for the below Transition Rules:
TransitionRule[Gap +03:30 to +04:30, MARCH 21 at 00:00 WALL, standard offset +03:30]
TransitionRule[Overlap +04:30 to +03:30, SEPTEMBER 21 at 00:00 WALL, standard offset +03:30]
which corresponds to:
Rule Iran 2036 max - Mar 21 0:00 1:00 D
Rule Iran 2036 max - Sep 21 0:00 0 S

 
Obviously, ZoneRules.java:235 lacks null check for the DayOfWeek field of ZoneOffsetTransitionRule.
 
As per the ZoneOffsetTransitionRule constructor definition:
"@param dayOfWeek the required day-of-week, null if the month-day should not be changed"
 
All other parameters are "not null", so need for the null check while reading and writing those.
 
Solution: Before getting day-of-week value(an integer value from 1 to 7) from DayOfWeek field of ZoneOffsetTransitionRule a null check is necessary in ZoneRules.java line no. 235