Type alias AsyncPTransform<InputT, OutputT>
AsyncPTransform<InputT, OutputT>: AsyncPTransformClass<InputT, OutputT> | ((input: InputT) => Promise<OutputT>) | ((input: InputT, pipeline: Pipeline, transformProto: runnerApi.PTransform) => Promise<OutputT>)
An AsyncPTransform is simply a PTransform that returns a Promise rather than a concrete result. This is required when the construction itself needs to invoke asynchronous methods, and the returned promise must be awaited (or chained) before further construction.