68     /**
  69      * Returns the {@link HttpConnection} instance to which this exchange is
  70      * assigned.
  71      */
  72     abstract HttpConnection connection();
  73 
  74     /**
  75      * Initiates a new exchange and assigns it to a connection if one exists
  76      * already. connection usually null.
  77      */
  78     static <U> CompletableFuture<? extends ExchangeImpl<U>>
  79     get(Exchange<U> exchange, HttpConnection connection)
  80     {
  81         if (exchange.version() == HTTP_1_1) {
  82             if (debug.on())
  83                 debug.log("get: HTTP/1.1: new Http1Exchange");
  84             return createHttp1Exchange(exchange, connection);
  85         } else {
  86             Http2ClientImpl c2 = exchange.client().client2(); // #### improve
  87             HttpRequestImpl request = exchange.request();
  88             CompletableFuture<Http2Connection> c2f = c2.getConnectionFor(request);
  89             if (debug.on())
  90                 debug.log("get: Trying to get HTTP/2 connection");
  91             return c2f.handle((h2c, t) -> createExchangeImpl(h2c, t, exchange, connection))
  92                     .thenCompose(Function.identity());
  93         }
  94     }
  95 
  96     private static <U> CompletableFuture<? extends ExchangeImpl<U>>
  97     createExchangeImpl(Http2Connection c,
  98                        Throwable t,
  99                        Exchange<U> exchange,
 100                        HttpConnection connection)
 101     {
 102         if (debug.on())
 103             debug.log("handling HTTP/2 connection creation result");
 104         boolean secure = exchange.request().secure();
 105         if (t != null) {
 106             if (debug.on())
 107                 debug.log("handling HTTP/2 connection creation failed: %s",
 108                                  (Object)t);

  68     /**
  69      * Returns the {@link HttpConnection} instance to which this exchange is
  70      * assigned.
  71      */
  72     abstract HttpConnection connection();
  73 
  74     /**
  75      * Initiates a new exchange and assigns it to a connection if one exists
  76      * already. connection usually null.
  77      */
  78     static <U> CompletableFuture<? extends ExchangeImpl<U>>
  79     get(Exchange<U> exchange, HttpConnection connection)
  80     {
  81         if (exchange.version() == HTTP_1_1) {
  82             if (debug.on())
  83                 debug.log("get: HTTP/1.1: new Http1Exchange");
  84             return createHttp1Exchange(exchange, connection);
  85         } else {
  86             Http2ClientImpl c2 = exchange.client().client2(); // #### improve
  87             HttpRequestImpl request = exchange.request();
  88             CompletableFuture<Http2Connection> c2f = c2.getConnectionFor(request, exchange);
  89             if (debug.on())
  90                 debug.log("get: Trying to get HTTP/2 connection");
  91             return c2f.handle((h2c, t) -> createExchangeImpl(h2c, t, exchange, connection))
  92                     .thenCompose(Function.identity());
  93         }
  94     }
  95 
  96     private static <U> CompletableFuture<? extends ExchangeImpl<U>>
  97     createExchangeImpl(Http2Connection c,
  98                        Throwable t,
  99                        Exchange<U> exchange,
 100                        HttpConnection connection)
 101     {
 102         if (debug.on())
 103             debug.log("handling HTTP/2 connection creation result");
 104         boolean secure = exchange.request().secure();
 105         if (t != null) {
 106             if (debug.on())
 107                 debug.log("handling HTTP/2 connection creation failed: %s",
 108                                  (Object)t);