question: @ Override public Scorer scorer ( LeafReaderContext context ) throws IOException { List < Scorer > scorers = new ArrayList < > ( ) ; for ( Weight w : weights ) { Scorer subScorer = w . scorer ( context ) ; if ( subScorer != null ) { scorers . add ( subScorer ) ; } } if ( scorers . isEmpty ( ) ) { return null ; } else if ( scorers . size ( ) == 1 ) { return scorers . get ( 0 ) ; } else { return new DisjunctionMaxScorer ( this , tieBreakerMultiplier , scorers , needsScores ) ; } }
target:  Create the scorer used to score our associated DisjunctionMaxQuery 