fix: Fail connectivity checks for non-keep-alive pairs (#304)

* fix: Fail connectivity checks for non-keep-alive pairs

This covers a case that was missed in #287. When multiple pairs
are SUCCEEDED before we reach the TERMINATED state, we keep responding
to them.

Author: bgrozev

src/main/java/org/ice4j/ice/Agent.java

@@ -1703,6 +1703,16 @@ private boolean triggerCheck(CandidatePair triggerPair)
                     checkListStatesUpdated();
                 }
 
+                if (getState() == IceProcessingState.TERMINATED
+                        && knownPair.getParentComponent().getKeepAliveStrategy() != KeepAliveStrategy.ALL_SUCCEEDED)
+                {
+                    // After we've terminated, only respond for the selected pair
+                    CandidatePair selected
+                            = getSelectedPair(knownPair.getParentComponent().getParentStream().getName());
+                    return selected != null
+                            && knownPair.getRemoteCandidate().getTransportAddress().equals(
+                                    selected.getRemoteCandidate().getTransportAddress());
+                }
                 return true;
             }
 

src/main/java/org/ice4j/ice/Component.java

@@ -225,6 +225,11 @@ protected Component(int componentID,
         mediaStream.addPairChangeListener(this);
     }
 
+    public KeepAliveStrategy getKeepAliveStrategy()
+    {
+        return keepAliveStrategy;
+    }
+
     /**
      * Add a local candidate to this component. The method should only be
      * accessed and local candidates added by the candidate harvesters