public PublisherMapFuseable(Publisher<? extends T> source,Function<? super T,? extends R> mapper){
  super(source);
  if (!(source instanceof Fuseable)) {
    throw new IllegalArgumentException("The source must implement the Fuseable interface for this operator to work");
  }
  this.mapper=Objects.requireNonNull(mapper,"mapper");
}

public PublisherMapFuseable ( Publisher < ? extends T > source , Function < ? super T , ? extends R > mapper ) { super ( source ) ; if ( ! ( source instanceof Fuseable ) ) { throw new IllegalArgumentException ( "The source must implement the Fuseable interface for this operator to work" ) ; } this . mapper = Objects . requireNonNull ( mapper , "mapper" ) ; }
constructs a publishermap instance with the given source and mapper .
