@Override
  protected void serializeStateData(ProcedureStateSerializer serializer) throws IOException {
    SnapshotVerifyProcedureStateData.Builder builder =
      SnapshotVerifyProcedureStateData.newBuilder();
    builder.setSnapshot(snapshot).setRegion(ProtobufUtil.toRegionInfo(region)).setState(state);
    if (targetServer != null) {
      builder.setTargetServer(ProtobufUtil.toServerName(targetServer));
    }
    if (this.remoteError != null) {
      ErrorHandlingProtos.ForeignExceptionMessage fem =
        ForeignExceptionUtil.toProtoForeignException(remoteError);
      builder.setError(fem);
    }
    serializer.serialize(builder.build());
  }
A remote procedure which is used to send verify snapshot request to region server.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/SnapshotVerifyProcedure.java