public Optional<EventStreamInfo> getOutputInfo(ToShapeId operationShape) {
        return Optional.ofNullable(outputInfo.get(operationShape.toShapeId()));
    }
Get event stream information for the output of an operation.

<p>No result is returned if the provided operation shape does not
exist, if the targeted shape is not an operation, if the operation
does not contain an output structure or if the output structure does
not contain an output event stream.

@param operationShape Operation or shape ID to retrieve information for.
@return Returns the optionally found output event stream information.
smithy-model/src/main/java/software/amazon/smithy/model/knowledge/EventStreamIndex.java