question: static ZoneOffsetTransition readExternal ( DataInput in ) throws IOException { long epochSecond = Ser . readEpochSec ( in ) ; ZoneOffset before = Ser . readOffset ( in ) ; ZoneOffset after = Ser . readOffset ( in ) ; if ( before . equals ( after ) ) { throw new IllegalArgumentException ( "Offsets must not be equal" ) ; } return new ZoneOffsetTransition ( epochSecond , before , after ) ; }
target:  Reads the state from the stream.