8312818: Incorrect format specifier in a HttpClient log message

Reviewed-by: djelinski

Author: jaikiran

src/java.net.http/share/classes/jdk/internal/net/http/HttpClientImpl.java

@@ -1525,7 +1525,7 @@ void register(AsyncEvent e) throws ClosedChannelException {
             interestOps |= newOps;
             pending.add(e);
             if (debug.on())
-                debug.log("Registering %s for %d (%s)",
+                debug.log("Registering %s for %s (%s)",
                         e, Utils.describeOps(newOps), reRegister);
             if (reRegister) {
                 // first time registration happens here also