@UnstableApi
    @Nullable
    default Boolean isResponseStreaming(Type returnType, @Nullable MediaType produceType) {
        // TODO(ikhoon): Make this method an abstract method in Armeria 2.0 so that users always implement
        //               this method to explicitly set whether to support response streaming for
        //               the `returnType`.
        return true;
    }
Returns whether an {@link HttpResponse} of an annotated service should be streamed.
{@code null} if this converter cannot convert the {@code responseType} to an {@link HttpResponse}.
{@code true} can be returned if the response is a streaming type, or the
{@link ResponseConverterFunction} has not been optimized for the {@code responseType} through overriding
this method for backward compatibility.

<p>This method is used as a performance optimization hint.
If the {@code returnType} and {@code produceType} are not a streaming response,
it is recommended to return {@code false} for the better performance.

<p>Note that you should never return {@code false} for a streaming response.
The non-streaming response is aggregated before being sent.

@param returnType the return type of the annotated service.
@param produceType the negotiated producible media type of the annotated service.
                   {@code null} if the media type negotiation is not used for the service.
core/src/main/java/com/linecorp/armeria/server/annotation/ResponseConverterFunction.java