Unable to compile cpp metastore thrift client

struct SourceTable {
    1: required Table table,
   ...
}

struct CreationMetadata {
    ...
    7: optional set<SourceTable> sourceTables
}

struct Table {
  ...
  16: optional CreationMetadata creationMetadata,   // only for MVs, it stores table names used and txn list at MV creation
  ...
}