Add toString() for debugging and logging.

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1794646 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/httpcore5/src/main/java/org/apache/hc/core5/reactor/ListenerEndpointImpl.java b/httpcore5/src/main/java/org/apache/hc/core5/reactor/ListenerEndpointImpl.java
index 45b54e6..ace97ba 100644
--- a/httpcore5/src/main/java/org/apache/hc/core5/reactor/ListenerEndpointImpl.java
+++ b/httpcore5/src/main/java/org/apache/hc/core5/reactor/ListenerEndpointImpl.java
@@ -76,6 +76,12 @@
     }
 
     @Override
+    public String toString() {
+        return "[address=" + address + ", key=" + key + ", closed=" + closed + ", completed="
+                + completed + ", exception=" + exception + ", callback=" + callback + "]";
+    }
+
+    @Override
     public void waitFor() throws InterruptedException {
         if (this.completed) {
             return;