Java exception while constructing KStream

WARN  10-27 03:29:29.958 o.k.c.i.t.j.RomClientJsonRpcClient:243 [EventExec-e3-t1] - [Continuation] error invoking OnSuccess implemented by client
java.lang.NullPointerException: null
at java.base/java.lang.reflect.Proxy.getInvocationHandler(Proxy.java:1102)
at org.kurento.client.internal.client.RemoteObjectInvocationHandler.getFor(RemoteObjectInvocationHandler.java:72)
at org.kurento.client.AbstractBuilder.<init>(AbstractBuilder.java:46)
at org.kurento.client.WebRtcEndpoint$Builder.<init>(WebRtcEndpoint.java:2199)
at org.apache.openmeetings.core.remote.AbstractStream.createWebRtcEndpoint(AbstractStream.java:51)
at org.apache.openmeetings.core.remote.KStream.createEndpoint(KStream.java:250)
at org.apache.openmeetings.core.remote.KStream.internalStartBroadcast(KStream.java:148)
at org.apache.openmeetings.core.remote.KStream$1.onSuccess(KStream.java:136)
at org.apache.openmeetings.core.remote.KStream$1.onSuccess(KStream.java:133)
at org.kurento.client.internal.client.RomManager$3.onSuccess(RomManager.java:229)
at org.kurento.client.internal.client.RomManager$3.onSuccess(RomManager.java:226)
at org.kurento.client.internal.transport.jsonrpc.RomClientJsonRpcClient$3.onSuccess(RomClientJsonRpcClient.java:377)
at org.kurento.client.internal.transport.jsonrpc.RomClientJsonRpcClient$3.onSuccess(RomClientJsonRpcClient.java:373)
at org.kurento.client.internal.transport.jsonrpc.RomClientJsonRpcClient$2.onSuccess(RomClientJsonRpcClient.java:241)
at org.kurento.client.internal.transport.jsonrpc.RomClientJsonRpcClient$2.onSuccess(RomClientJsonRpcClient.java:233)
at org.kurento.jsonrpc.internal.JsonRpcRequestSenderHelper$1.onSuccess(JsonRpcRequestSenderHelper.java:130)
at org.kurento.jsonrpc.internal.JsonRpcRequestSenderHelper$1.onSuccess(JsonRpcRequestSenderHelper.java:113)
at org.kurento.jsonrpc.client.AbstractJsonRpcClientWebSocket$14.onSuccess(AbstractJsonRpcClientWebSocket.java:452)
at org.kurento.jsonrpc.client.AbstractJsonRpcClientWebSocket$14.onSuccess(AbstractJsonRpcClientWebSocket.java:433)
at com.google.common.util.concurrent.Futures$CallbackListener.run(Futures.java:1089)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)