codec null handling fixed

src/main/java/org/redisson/client/handler/CommandDecoder.java

@@ -112,7 +112,11 @@ public class CommandDecoder extends ReplayingDecoder<Void> {
             Object result = Long.valueOf(status);
             handleResult(data, parts, result);
         } else if (code == '$') {
-            Object result = decoder(data, parts, currentDecoder).decode(readBytes(in));
+            ByteBuf buf = readBytes(in);
+            Object result = null;
+            if (buf != null) {
+                result = decoder(data, parts, currentDecoder).decode(buf);
+            }
             handleResult(data, parts, result);
         } else if (code == '*') {
             long size = readLong(in);

src/main/java/org/redisson/client/protocol/LongCodec.java

@@ -27,9 +27,6 @@ public class LongCodec extends StringCodec {
         return new Decoder<Object>() {
             @Override
             public Object decode(ByteBuf buf) {
-                if (buf == null) {
-                    return null;
-                }
                 return Long.valueOf(buf.toString(CharsetUtil.UTF_8));
             }
         };

src/main/java/org/redisson/client/protocol/StringCodec.java

@@ -29,9 +29,6 @@ public class StringCodec implements Codec {
         return new Decoder<Object>() {
             @Override
             public Object decode(ByteBuf buf) {
-                if (buf == null) {
-                    return null;
-                }
                 return buf.toString(CharsetUtil.UTF_8);
             }
         };

src/main/java/org/redisson/codec/JsonJacksonCodec.java

@@ -97,10 +97,6 @@ public class JsonJacksonCodec implements Codec {
 
             @Override
             public Object decode(ByteBuf buf) throws IOException {
-                if (buf == null) {
-                    return null;
-                }
-
                 return mapObjectMapper.readValue(new ByteBufInputStream(buf), Object.class);
             }
         };

src/test/java/org/redisson/RedissonMapTest.java

@@ -441,6 +441,14 @@ public class RedissonMapTest extends BaseTest {
         Assert.assertEquals(3, map.size());
     }
 
+    @Test
+    public void testEmptyRemove() {
+        RMap<Integer, Integer> map = redisson.getMap("simple");
+        Assert.assertFalse(map.remove(1, 3));
+        map.put(4, 5);
+        Assert.assertTrue(map.remove(4, 5));
+    }
+
     @Test
     public void testPutAsync() throws InterruptedException, ExecutionException {
         RMap<Integer, Integer> map = redisson.getMap("simple");