code: protected String parseEdgeOrientation(String v) {
          if (v == null) {
              return null;
          }
          if (!v.contains(SEPARATOR)) {
              throw new IllegalArgumentException(ORIENTATION_ERROR);
          }
          // Extract the global and edge orientations.
          String[] s = v.split(SEPARATOR);
          if (s.length == 2) {
              // Return just the edge orientation column name and not the
              // global orientation.
              return s[1].trim();
          } else {
              throw new IllegalArgumentException(ORIENTATION_ERROR);
          }
      }
docs: Recovers the edge orientation from a string.
  
  @param v String
  @return The edge orientation