Implement connectionCheckOutStarted in the ConnectionPoolListenerMulticaster (#669)

JAVA-4015

Author: rozza

driver-core/src/main/com/mongodb/internal/event/ConnectionPoolListenerMulticaster.java

@@ -19,6 +19,7 @@
 import com.mongodb.diagnostics.logging.Logger;
 import com.mongodb.diagnostics.logging.Loggers;
 import com.mongodb.event.ConnectionCheckOutFailedEvent;
+import com.mongodb.event.ConnectionCheckOutStartedEvent;
 import com.mongodb.event.ConnectionCheckedInEvent;
 import com.mongodb.event.ConnectionCheckedOutEvent;
 import com.mongodb.event.ConnectionClosedEvent;
@@ -98,6 +99,19 @@ public void connectionPoolClosed(final ConnectionPoolClosedEvent event) {
         }
     }
 
+    @Override
+    public void connectionCheckOutStarted(final ConnectionCheckOutStartedEvent event) {
+        for (ConnectionPoolListener cur : connectionPoolListeners) {
+            try {
+                cur.connectionCheckOutStarted(event);
+            } catch (Exception e) {
+                if (LOGGER.isWarnEnabled()) {
+                    LOGGER.warn(format("Exception thrown raising connection check out started event to listener %s", cur), e);
+                }
+            }
+        }
+    }
+
     @Override
     public void connectionCheckedOut(final ConnectionCheckedOutEvent event) {
         for (ConnectionPoolListener cur : connectionPoolListeners) {