code: public String find(String named) {
      File file = new File(named);
      if (canExecute(file)) {
        return named;
      }
  
      if (Platform.getCurrent().is(Platform.WINDOWS)) {
        file = new File(named + ".exe");
        if (canExecute(file)) {
          return named + ".exe";
        }
      }
  
      addPathFromEnvironment();
      if (Platform.getCurrent().is(Platform.MAC)) {
        addMacSpecificPath();
      }
  
      for (String pathSegment : pathSegmentBuilder.build()) {
        for (String ending : ENDINGS) {
          file = new File(pathSegment, named + ending);
          if (canExecute(file)) {
            return file.getAbsolutePath();
          }
        }
      }
      return null;
    }
docs: Find the executable by scanning the file system and the PATH. In the case of Windows this
  method allows common executable endings (".com", ".bat" and ".exe") to be omitted.
  
  @param named The name of the executable to find
  @return The absolute path to the executable, or null if no match is made.