docs: public void flattenToBufferForOriginalVersion(ByteBuffer buf) throws IOException
      {
          assert((params != null) || (serializedParams != null));
  
          // for self-check assertion
          int startPosition = buf.position();
  
          buf.put(ProcedureInvocationType.ORIGINAL.getValue());
  
          SerializationHelper.writeVarbinary(getProcNameBytes(), buf);
  
          buf.putLong(clientHandle);
  
          serializeParams(buf);
  
          int len = buf.position() - startPosition;
          assert(len == getSerializedSizeForOriginalVersion());
      }