Dispose Existing Connection and Thread Pools

Previously, the DefaultConnectionContext did not cache the connection and
thread pools that it used. This meant that new instances of these resources
were created when dispose was called, and the originals were never disposed.
This change caches those connection and thread pools so that they are properly
disposed.

[resolves #815]

Author: nebhale

cloudfoundry-client-reactor/src/main/java/org/cloudfoundry/reactor/_DefaultConnectionContext.java

@@ -141,6 +141,12 @@ public void trust(String host, int port) {
      */
     abstract Optional<Duration> getConnectTimeout();
 
+    @Value.Derived
+    Optional<PoolResources> getConnectionPool() {
+        return Optional.ofNullable(getConnectionPoolSize())
+            .map(connectionPoolSize -> PoolResources.fixed("cloudfoundry-client", connectionPoolSize));
+    }
+
     /**
      * The {@code SO_KEEPALIVE} value
      */
@@ -195,12 +201,8 @@ Optional<SslCertificateTruster> getSslCertificateTruster() {
      */
     abstract Optional<Duration> getSslHandshakeTimeout();
 
-    private Optional<PoolResources> getConnectionPool() {
-        return Optional.ofNullable(getConnectionPoolSize())
-            .map(connectionPoolSize -> PoolResources.fixed("cloudfoundry-client", connectionPoolSize));
-    }
-
-    private LoopResources getThreadPool() {
+    @Value.Derived
+    LoopResources getThreadPool() {
         return LoopResources.create("cloudfoundry-client", getThreadPoolSize(), true);
     }