code: private File createWorkingDirectory( String workingDirectoryOption )
      {
          final File workDir = new File( workingDirectoryOption );
          // create if not existent:
          if( !workDir.exists() )
          {
              workDir.mkdirs();
          }
          if( m_workingFolder == null )
          {
              m_workingFolder = workDir;
          }
          return workDir;
      }
docs: Creates by default a working directory as ${java.io.tmpdir}/paxexam_runner_${user.name}.
  Unless manualWorkingDirectory is set.
  
  @param workingDirectoryOption
  
  @return created working directory