code: Set<OpensFlag> readOpensFlags(int flags) {
          Set<OpensFlag> set = EnumSet.noneOf(OpensFlag.class);
          for (OpensFlag f: OpensFlag.values()) {
              if ((flags & f.value) != 0)
                  set.add(f);
          }
          return set;
      }
docs: Read opens_flags.