code: public IndexEntry findEntry(String partName, long partFileOffset) {
      for (IndexEntry e: entries) {
        boolean nameMatch = partName.equals(e.partFileName);
        boolean inRange = (partFileOffset >= e.startOffset) &&
                          (partFileOffset < e.startOffset + e.length);
        if (nameMatch && inRange) {
          return e;
        }
      }
      return null;
    }
docs: Finds the index entry corresponding to a HAR partFile at an offset.
  @param partName The name of the part file (part-*).
  @param partFileOffset The offset into the part file.
  @return The entry corresponding to partName:partFileOffset.