question: protected long findLatestFileNameGeneration ( Map < String , BlobMetaData > blobs ) { long generation = - 1 ; for ( String name : blobs . keySet ( ) ) { if ( ! name . startsWith ( DATA_BLOB_PREFIX ) ) { continue ; } name = FileInfo . canonicalName ( name ) ; try { long currentGen = Long . parseLong ( name . substring ( DATA_BLOB_PREFIX . length ( ) ) , Character . MAX_RADIX ) ; if ( currentGen > generation ) { generation = currentGen ; } } catch ( NumberFormatException e ) { logger . warn ( "file [{}] does not conform to the '{}' schema" , name , DATA_BLOB_PREFIX ) ; } } return generation ; }
target:  Finds the next available blob number