--- a/src/java.net.http/share/classes/jdk/internal/net/http/ConnectionPool.java	Mon Sep 09 10:13:42 2019 -0700
+++ b/src/java.net.http/share/classes/jdk/internal/net/http/ConnectionPool.java	Mon Sep 09 18:23:39 2019 +0100
@@ -138,6 +138,8 @@
                                               InetSocketAddress addr,
                                               InetSocketAddress proxy) {
         if (stopped) return null;
+        // for plain (unsecure) proxy connection the destination address is irrelevant.
+        addr = secure || proxy == null ? addr : null;
         CacheKey key = new CacheKey(addr, proxy);
         HttpConnection c = secure ? findConnection(key, sslPool)
                                   : findConnection(key, plainPool);