private rpc(method: string, requestData: Buffer, callback: UnaryCallback<Buffer>, authToken?: string) { const serializeF = (request: Buffer) => request const deSerializeF = (response: Buffer) => response const metadata = new Metadata() if (authToken) { metadata.set('Authorization', authToken) } this.rpcClient.makeUnaryRequest( `contractregistry.ContractRegistry/${method}`, serializeF, deSerializeF, requestData, metadata, callback ) }