code: public static final Set<? extends OpenOption> getOpenOptions(Path path, Map<String, ?> env) throws IOException
      {
          Set<? extends OpenOption> opts = (Set<? extends OpenOption>) env.get(OPEN_OPTIONS);
          if (opts == null)
          {
              if (Files.exists(path) && Files.size(path) > 0)
              {
                  opts = EnumSet.of(READ);
              }
              else
              {
                  opts = EnumSet.of(WRITE, CREATE);
              }
          }
          return opts;
      }
docs: Returns open-options. Returns from env if exists. Otherwise if file exists
  and size greater than 0 returns READ or READ,WRITE.
  @param path
  @param env
  @return
  @throws IOException