code: public static FileReader createFileReader(String className, LogFilePath logFilePath,
                                                CompressionCodec codec,
                                                SecorConfig config)
              throws Exception {
          return createFileReaderWriterFactory(className, config).BuildFileReader(logFilePath, codec);
      }
docs: Use the FileReaderWriterFactory specified by className to build a FileReader
  
  @param className the class name of a subclass of FileReaderWriterFactory to create a FileReader from
  @param logFilePath the LogFilePath that the returned FileReader should read from
  @param codec an instance CompressionCodec to decompress the file being read, or null for no compression
  @param config The SecorCondig to initialize the FileReader with
  @return a FileReader specialised to read the type of files supported by the FileReaderWriterFactory
  @throws Exception on error