optimize some code (#9289)

Motivation:

There is some manual coping of elements of Collections which can be replaced by Collections.addAll(...) and also some unnecessary semicolons.

Modifications:

- Simplify branches
- Use Collections.addAll
- Code cleanup

Result:

Code cleanup

codec-http2/src/main/java/io/netty/handler/codec/http2/Http2Exception.java

@@ -225,7 +225,7 @@ public class Http2Exception extends Exception {
         /**
          * Close the channel immediately after a {@code GOAWAY} is sent.
          */
-        HARD_SHUTDOWN;
+        HARD_SHUTDOWN
     }
 
     /**

codec-smtp/src/main/java/io/netty/handler/codec/smtp/SmtpRequests.java

@@ -20,6 +20,7 @@ import io.netty.util.internal.ObjectUtil;
 import io.netty.util.internal.UnstableApi;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 /**
@@ -94,9 +95,7 @@ public final class SmtpRequests {
         } else {
             List<CharSequence> params = new ArrayList<CharSequence>(mailParameters.length + 1);
             params.add(sender != null? "FROM:<" + sender + '>' : FROM_NULL_SENDER);
-            for (CharSequence param : mailParameters) {
-                params.add(param);
-            }
+            Collections.addAll(params, mailParameters);
             return new DefaultSmtpRequest(SmtpCommand.MAIL, params);
         }
     }
@@ -111,9 +110,7 @@ public final class SmtpRequests {
         } else {
             List<CharSequence> params = new ArrayList<CharSequence>(rcptParameters.length + 1);
             params.add("TO:<" + recipient + '>');
-            for (CharSequence param : rcptParameters) {
-                params.add(param);
-            }
+            Collections.addAll(params, rcptParameters);
             return new DefaultSmtpRequest(SmtpCommand.RCPT, params);
         }
     }

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

@@ -15,14 +15,6 @@
  */
 package io.netty.handler.codec;
 
-import io.netty.buffer.ByteBuf;
-import io.netty.buffer.ByteBufAllocator;
-import io.netty.buffer.SwappedByteBuf;
-import io.netty.buffer.Unpooled;
-import io.netty.util.ByteProcessor;
-import io.netty.util.Signal;
-import io.netty.util.internal.StringUtil;
-
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
@@ -32,6 +24,14 @@ import java.nio.channels.GatheringByteChannel;
 import java.nio.channels.ScatteringByteChannel;
 import java.nio.charset.Charset;
 
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufAllocator;
+import io.netty.buffer.SwappedByteBuf;
+import io.netty.buffer.Unpooled;
+import io.netty.util.ByteProcessor;
+import io.netty.util.Signal;
+import io.netty.util.internal.StringUtil;
+
 /**
  * Special {@link ByteBuf} implementation which is used by the {@link ReplayingDecoder}
  */
@@ -488,12 +488,12 @@ final class ReplayingDecoderByteBuf extends ByteBuf {
 
     @Override
     public boolean isReadable() {
-        return terminated? buffer.isReadable() : true;
+        return !terminated || buffer.isReadable();
     }
 
     @Override
     public boolean isReadable(int size) {
-        return terminated? buffer.isReadable(size) : true;
+        return !terminated || buffer.isReadable(size);
     }
 
     @Override

common/src/test/java/io/netty/util/internal/logging/Log4J2LoggerTest.java

@@ -50,7 +50,7 @@ public class Log4J2LoggerTest extends AbstractInternalLoggerTest<Logger> {
                 result.put("level", level.name());
                 result.put("t", t);
                 super.logMessage(fqcn, level, marker, message, t);
-            };
+            }
         };
     }
 

handler/src/main/java/io/netty/handler/ssl/JdkSslContext.java

@@ -102,9 +102,7 @@ public class JdkSslContext extends SslContext {
         // Choose the sensible default list of protocols.
         final String[] supportedProtocols = engine.getSupportedProtocols();
         Set<String> supportedProtocolsSet = new HashSet<String>(supportedProtocols.length);
-        for (int i = 0; i < supportedProtocols.length; ++i) {
-            supportedProtocolsSet.add(supportedProtocols[i]);
-        }
+        Collections.addAll(supportedProtocolsSet, supportedProtocols);
         List<String> protocols = new ArrayList<String>();
         addIfSupported(
                 supportedProtocolsSet, protocols,

handler/src/main/java/io/netty/handler/ssl/SslUtils.java

@@ -123,9 +123,7 @@ final class SslUtils {
         // AES256 requires JCE unlimited strength jurisdiction policy files.
         defaultCiphers.add("TLS_RSA_WITH_AES_256_CBC_SHA");
 
-        for (String tlsv13Cipher: DEFAULT_TLSV13_CIPHER_SUITES) {
-            defaultCiphers.add(tlsv13Cipher);
-        }
+        Collections.addAll(defaultCiphers, DEFAULT_TLSV13_CIPHER_SUITES);
 
         DEFAULT_CIPHER_SUITES = defaultCiphers.toArray(new String[0]);
     }