message: Fill up data field for summary acks and nacks
diff: @@ -9,13 +9,13 @@ import assert from "assert";
  import { inspect } from "util";
  import { ProtocolOpHandler } from "@fluidframework/protocol-base";
  import {
  - IDocumentMessage,
  IDocumentSystemMessage,
  ISequencedDocumentMessage,
  ISummaryAck,
  ISummaryNack,
  MessageType,
  ISequencedDocumentAugmentedMessage,
  + ISequencedDocumentSystemMessage,
  IProtocolState,
  } from "@fluidframework/protocol-definitions";
  import { DocumentContext } from "@fluidframework/server-lambdas-driver";
  @@ -345,7 +345,8 @@ export class ScribeLambda implements IPartitionLambda {
  }
  }
  } else if (value.operation.type === MessageType.SummaryAck) {
  - const content = value.operation.contents as ISummaryAck;
  + const operation = value.operation as ISequencedDocumentSystemMessage;
  + const content: ISummaryAck = operation.data ? JSON.parse(operation.data) : operation.contents;
  this.lastClientSummaryHead = content.handle;
  // An external summary writer can only update the protocolHead when the ack is sequenced
  // back to the stream.
  @@ -514,9 +515,10 @@ export class ScribeLambda implements IPartitionLambda {
  }
  private async sendSummaryAck(contents: ISummaryAck) {
  - const operation: IDocumentMessage = {
  + const operation: IDocumentSystemMessage = {
  clientSequenceNumber: -1,
  contents,
  + data: JSON.stringify(contents),
  referenceSequenceNumber: -1,
  traces: this.serviceConfiguration.enableTraces ? [] : undefined,
  type: MessageType.SummaryAck,
  @@ -526,9 +528,10 @@ export class ScribeLambda implements IPartitionLambda {
  }
  private async sendSummaryNack(contents: ISummaryNack) {
  - const operation: IDocumentMessage = {
  + const operation: IDocumentSystemMessage = {
  clientSequenceNumber: -1,
  contents,
  + data: JSON.stringify(contents),
  referenceSequenceNumber: -1,
  traces: this.serviceConfiguration.enableTraces ? [] : undefined,
  type: MessageType.SummaryNack,
  