question: private void fetchFileList ( long gen ) throws IOException { ModifiableSolrParams params = new ModifiableSolrParams ( ) ; params . set ( COMMAND , CMD_GET_FILE_LIST ) ; params . set ( GENERATION , String . valueOf ( gen ) ) ; params . set ( CommonParams . WT , "javabin" ) ; params . set ( CommonParams . QT , "/replication" ) ; QueryRequest req = new QueryRequest ( params ) ; HttpSolrServer server = new HttpSolrServer ( masterUrl , myHttpClient ) ; try { server . setSoTimeout ( 60000 ) ; server . setConnectionTimeout ( 15000 ) ; NamedList response = server . request ( req ) ; List < Map < String , Object > > files = ( List < Map < String , Object > > ) response . get ( CMD_GET_FILE_LIST ) ; if ( files != null ) filesToDownload = Collections . synchronizedList ( files ) ; else { filesToDownload = Collections . emptyList ( ) ; LOG . error ( "No files to download for index generation: " + gen ) ; } files = ( List < Map < String , Object > > ) response . get ( CONF_FILES ) ; if ( files != null ) confFilesToDownload = Collections . synchronizedList ( files ) ; } catch ( SolrServerException e ) { throw new IOException ( e ) ; } finally { server . shutdown ( ) ; } }
target:  Fetches the list of files in a given index commit point and updates internal list of files to download.