[border-agent] try getting coap dtls session from ephemeral key manager

Author: gytxxsy

src/core/meshcop/border_agent.cpp

@@ -280,6 +280,14 @@ BorderAgent::CoapDtlsSession *BorderAgent::FindActiveCommissionerSession(void)
         }
     }
 
+#if OPENTHREAD_CONFIG_BORDER_AGENT_EPHEMERAL_KEY_ENABLE
+    CoapDtlsSession *coapSession = GetEphemeralKeyManager().mCoapDtlsSession;
+    if (coapSession && coapSession->IsActiveCommissioner())
+    {
+        commissionerSession = coapSession;
+    }
+#endif
+
     return commissionerSession;
 }