String subcontainerIndex() {
      if (index < 0) {
        return "";
      }
      StringBuilder version = new StringBuilder();
      EOFParseStep current = this;
      while (current != null) {
        var prev = current.parent;
        if (prev == null) {
          version.insert(0, index);
          break;
        } else {
          version.insert(0, '.');
          version.insert(1, current.index);
        }
        current = prev;
      }
      return version.toString();
    }
Parse EOF.

@param container the container
@return the eof layout
evm/src/main/java/org/hyperledger/besu/evm/code/EOFLayout.java