question: public static Map < String , List < DataFileFooter > > createDataFileFooterMappingForSegments ( List < TableBlockInfo > tableBlockInfoList ) throws IndexBuilderException { Map < String , List < DataFileFooter > > segmentBlockInfoMapping = new HashMap < > ( ) ; for ( TableBlockInfo blockInfo : tableBlockInfoList ) { List < DataFileFooter > eachSegmentBlocks = new ArrayList < > ( ) ; String segId = blockInfo . getSegmentId ( ) ; DataFileFooter dataFileMatadata = null ; List < DataFileFooter > metadataList = segmentBlockInfoMapping . get ( segId ) ; try { dataFileMatadata = CarbonUtil . readMetadatFile ( blockInfo . getFilePath ( ) , blockInfo . getBlockOffset ( ) , blockInfo . getBlockLength ( ) ) ; } catch ( CarbonUtilException e ) { throw new IndexBuilderException ( e ) ; } if ( null == metadataList ) { eachSegmentBlocks . add ( dataFileMatadata ) ; segmentBlockInfoMapping . put ( segId , eachSegmentBlocks ) ; } else { metadataList . add ( dataFileMatadata ) ; } } return segmentBlockInfoMapping ; }
target:  To create a mapping of Segment Id and DataFileFooter.