code: public int execute(String[] args) {
          Map<String, LevelDetails> levels = readLevels(System.getProperty("logviewer.custom.levels"));
          String[] header = readHeader(System.getProperty("logviewer.custom.header"));
  
          return execute(args, levels, header);
      }
docs: Runs LogViewer using values in System Properties to find custom levels and header.
  
  @param args
  - command line arguments to LogViewer
  @return code indicating status of the execution: 0 on success, 1 otherwise.