Fixed - RStream.readGroup method doesn't handle empty result properly with Redis 5.0.3 #1978

redisson/src/main/java/org/redisson/client/protocol/decoder/ObjectDecoder.java

@@ -41,7 +41,8 @@ public class ObjectDecoder implements MultiDecoder<Object> {
 
     @Override
     public Object decode(List<Object> parts, State state) {
-        throw new IllegalStateException();
+        parts.clear();
+        return parts;
     }
 
 }

redisson/src/main/java/org/redisson/client/protocol/decoder/StreamIdDecoder.java

@@ -35,6 +35,9 @@ public class StreamIdDecoder implements Decoder<Object> {
     public Object decode(ByteBuf buf, State state) throws IOException {
         String id = (String) StringCodec.INSTANCE.getValueDecoder().decode(buf, state);
         String[] parts = id.toString().split("-");
+        if (parts.length == 1) {
+            return null;
+        }
         return new StreamMessageId(Long.valueOf(parts[0]), Long.valueOf(parts[1]));
     }
 

redisson/src/main/java/org/redisson/client/protocol/decoder/StreamObjectMapReplayDecoder.java

@@ -15,6 +15,7 @@
  */
 package org.redisson.client.protocol.decoder;
 
+import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -41,6 +42,12 @@ public class StreamObjectMapReplayDecoder extends ObjectMapReplayDecoder {
 
     @Override
     public Map<Object, Object> decode(List<Object> parts, State state) {
+        if (parts.get(0) == null
+                || (parts.get(0) instanceof List && ((List) parts.get(0)).isEmpty())) {
+            parts.clear();
+            return Collections.emptyMap();
+        }
+
         if (parts.get(0) instanceof Map) {
             Map<Object, Object> result = new LinkedHashMap<Object, Object>(parts.size());
             for (int i = 0; i < parts.size(); i++) {