Simplify redundant if-block (netty#12376)

Motivation:
We can simplify redundant `if-blocks` to make the code look simpler.

Modification:
Replaced `if-block` with simpler `boolean` statements.

Result:
Simpler code

Author: hyperxpro

codec-dns/src/main/java/io/netty/handler/codec/dns/DatagramDnsResponse.java

@@ -202,14 +202,10 @@ public boolean equals(Object obj) {
         }
 
         if (recipient() == null) {
-            if (that.recipient() != null) {
-                return false;
-            }
-        } else if (!recipient().equals(that.recipient())) {
-            return false;
+            return that.recipient() == null;
+        } else {
+            return recipient().equals(that.recipient());
         }
-
-        return true;
     }
 
     @Override

codec/src/main/java/io/netty/handler/codec/MessageAggregator.java

@@ -106,11 +106,9 @@ public boolean acceptInboundMessage(Object msg) throws Exception {
         if (isStartMessage(in)) {
             aggregating = true;
             return true;
-        } else if (aggregating && isContentMessage(in)) {
-            return true;
+        } else {
+            return aggregating && isContentMessage(in);
         }
-
-        return false;
     }
 
     /**

handler/src/main/java/io/netty/handler/timeout/IdleStateHandler.java

@@ -450,10 +450,7 @@ private boolean hasOutputChanged(ChannelHandlerContext ctx, boolean first) {
                 long flushProgress = buf.currentProgress();
                 if (flushProgress != lastFlushProgress) {
                     lastFlushProgress = flushProgress;
-
-                    if (!first) {
-                        return true;
-                    }
+                    return !first;
                 }
             }
         }

microbench/src/main/java/io/netty/microbenchmark/common/IsValidIpV6Benchmark.java

@@ -184,10 +184,8 @@ public static boolean isValidIpV6AddressOld(String ipAddress) {
         // Check if we have an IPv4 ending
         if (numberOfPeriods > 0) {
             // There is a test case with 7 colons and valid ipv4 this should resolve it
-            if (numberOfPeriods != 3 ||
-                !(isValidIp4Word(word.toString()) && (numberOfColons < 7 || doubleColon))) {
-                return false;
-            }
+            return numberOfPeriods == 3 &&
+                    (isValidIp4Word(word.toString()) && (numberOfColons < 7 || doubleColon));
         } else {
             // If we're at then end and we haven't had 7 colons then there is a
             // problem unless we encountered a doubleColon
@@ -199,16 +197,12 @@ public static boolean isValidIpV6AddressOld(String ipAddress) {
                 // If we have an empty word at the end, it means we ended in either
                 // a : or a .
                 // If we did not end in :: then this is invalid
-                if (ipAddress.charAt(endOffset - 1) == ':' &&
-                    ipAddress.charAt(endOffset - 2) != ':') {
-                    return false;
-                }
-            } else if (numberOfColons == 8 && ipAddress.charAt(startOffset) != ':') {
-                return false;
+                return ipAddress.charAt(endOffset - 1) != ':' ||
+                        ipAddress.charAt(endOffset - 2) == ':';
+            } else {
+                return numberOfColons != 8 || ipAddress.charAt(startOffset) == ':';
             }
         }
-
-        return true;
     }
 
     // Tests