public static ExchangeType of(boolean requestStreaming, boolean responseStreaming) {
        if (requestStreaming) {
            return responseStreaming ? BIDI_STREAMING : REQUEST_STREAMING;
        } else {
            return responseStreaming ? RESPONSE_STREAMING : UNARY;
        }
    }
Returns an {@link ExchangeType} with the specified {@code requestStreaming} and
{@code responseStreaming}.
core/src/main/java/com/linecorp/armeria/common/ExchangeType.java