Port log4j-api changes from 2.x

Ports minor changes in `log4j-api` from `2.x`.

Author: ppkarwasz

log4j-api/src/main/java/org/apache/logging/log4j/message/BasicThreadInformation.java

@@ -16,7 +16,9 @@
  */
 package org.apache.logging.log4j.message;
 
-import org.apache.logging.log4j.util.Chars;
+import static org.apache.logging.log4j.util.Chars.LF;
+import static org.apache.logging.log4j.util.Chars.SPACE;
+
 import org.apache.logging.log4j.util.StringBuilders;
 
 /**
@@ -78,16 +80,16 @@ public int hashCode() {
      */
     @Override
     public void printThreadInfo(final StringBuilder sb) {
-        StringBuilders.appendDqValue(sb, name).append(Chars.SPACE);
+        StringBuilders.appendDqValue(sb, name).append(SPACE);
         if (isDaemon) {
             sb.append("daemon ");
         }
         sb.append("prio=").append(priority).append(" tid=").append(id).append(' ');
         if (threadGroupName != null) {
             StringBuilders.appendKeyDqValue(sb, "group", threadGroupName);
         }
-        sb.append('\n');
-        sb.append("\tThread state: ").append(state.name()).append('\n');
+        sb.append(LF);
+        sb.append("\tThread state: ").append(state.name()).append(LF);
     }
 
     /**
@@ -98,7 +100,7 @@ public void printThreadInfo(final StringBuilder sb) {
     @Override
     public void printStack(final StringBuilder sb, final StackTraceElement[] trace) {
         for (final StackTraceElement element : trace) {
-            sb.append("\tat ").append(element).append('\n');
+            sb.append("\tat ").append(element).append(LF);
         }
     }
 }

log4j-api/src/main/java/org/apache/logging/log4j/message/FormattedMessageFactory.java

@@ -31,9 +31,7 @@ public class FormattedMessageFactory implements MessageFactory {
     /**
      * Constructs a message factory with default flow strings.
      */
-    public FormattedMessageFactory() {
-        super();
-    }
+    public FormattedMessageFactory() {}
 
     /**
      * Creates {@link StringFormattedMessage} instances.

log4j-api/src/main/java/org/apache/logging/log4j/message/LocalizedMessage.java

@@ -38,7 +38,7 @@ public class LocalizedMessage implements Message, LoggerNameAwareMessage {
 
     private final Locale locale;
 
-    private final StatusLogger logger = StatusLogger.getLogger();
+    private static final StatusLogger logger = StatusLogger.getLogger();
 
     private String loggerName;
     private final String key;

log4j-api/src/main/java/org/apache/logging/log4j/message/LocalizedMessageFactory.java

@@ -68,7 +68,7 @@ public ResourceBundle getResourceBundle() {
     @Override
     public Message newMessage(final String key) {
         if (resourceBundle == null) {
-            return new LocalizedMessage(baseName, key, null);
+            return new LocalizedMessage(baseName, key);
         }
         return new LocalizedMessage(resourceBundle, key);
     }

log4j-api/src/main/java/org/apache/logging/log4j/message/Message.java

@@ -73,6 +73,11 @@ public interface Message {
      *
      * @return The message format. Some implementations, such as ParameterizedMessage, will use this as
      * the message "pattern". Other Messages may simply return an empty String.
+     * TODO Do all messages have a format?  What syntax?  Using a Formatter object could be cleaner.
+     * (RG) In SimpleMessage the format is identical to the formatted message. In ParameterizedMessage and
+     * StructuredDataMessage it is not. It is up to the Message implementer to determine what this
+     * method will return. A Formatter is inappropriate as this is very specific to the Message
+     * implementation so it isn't clear to me how having a Formatter separate from the Message would be cleaner.
      */
     String getFormat();
 

log4j-api/src/main/java/org/apache/logging/log4j/message/ObjectArrayMessage.java

@@ -17,6 +17,7 @@
 package org.apache.logging.log4j.message;
 
 import java.util.Arrays;
+import org.apache.logging.log4j.util.Constants;
 
 /**
  * Handles messages that contain an Object[].
@@ -31,10 +32,8 @@
  */
 public final class ObjectArrayMessage implements Message {
 
-    private static final Object[] EMPTY_OBJECT_ARRAY = new Object[0];
-
-    private final transient Object[] array;
-    private transient String arrayString;
+    private final Object[] array;
+    private String arrayString;
 
     /**
      * Creates the ObjectMessage.
@@ -43,7 +42,7 @@ public final class ObjectArrayMessage implements Message {
      *            The Object to format.
      */
     public ObjectArrayMessage(final Object... obj) {
-        this.array = obj == null ? EMPTY_OBJECT_ARRAY : obj;
+        this.array = obj == null ? Constants.EMPTY_OBJECT_ARRAY : obj;
     }
 
     private boolean equalObjectsOrStrings(final Object[] left, final Object[] right) {

log4j-api/src/main/java/org/apache/logging/log4j/message/ObjectMessage.java

@@ -99,7 +99,7 @@ public boolean equals(final Object o) {
         }
 
         final ObjectMessage that = (ObjectMessage) o;
-        return equalObjectsOrStrings(obj, that.obj);
+        return obj == null ? that.obj == null : equalObjectsOrStrings(obj, that.obj);
     }
 
     private boolean equalObjectsOrStrings(final Object left, final Object right) {
@@ -108,7 +108,7 @@ private boolean equalObjectsOrStrings(final Object left, final Object right) {
 
     @Override
     public int hashCode() {
-        return obj.hashCode();
+        return obj != null ? obj.hashCode() : 0;
     }
 
     @Override

log4j-api/src/main/java/org/apache/logging/log4j/message/ParameterFormatter.java

@@ -60,8 +60,6 @@ final class ParameterFormatter {
     private static final char DELIM_START = '{';
     private static final char DELIM_STOP = '}';
     private static final char ESCAPE_CHAR = '\\';
-    private static final DateTimeFormatter FORMATTER =
-            DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ").withZone(ZoneId.systemDefault());
 
     private static final DateTimeFormatter DATE_FORMATTER =
             DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ").withZone(ZoneId.systemDefault());
@@ -439,7 +437,7 @@ private static boolean appendDate(final Object o, final StringBuilder str) {
         if (!(o instanceof Date)) {
             return false;
         }
-        str.append(FORMATTER.format(((Date) o).toInstant()));
+        str.append(DATE_FORMATTER.format(((Date) o).toInstant()));
         return true;
     }
 

log4j-api/src/main/java/org/apache/logging/log4j/message/ParameterizedNoReferenceMessageFactory.java

@@ -78,9 +78,7 @@ public Throwable getThrowable() {
     /**
      * Constructs a message factory with default flow strings.
      */
-    public ParameterizedNoReferenceMessageFactory() {
-        super();
-    }
+    public ParameterizedNoReferenceMessageFactory() {}
 
     /**
      * Instance of ParameterizedStatusMessageFactory.

log4j-api/src/main/java/org/apache/logging/log4j/message/ReusableMessageFactory.java

@@ -65,7 +65,7 @@ public ReusableMessageFactory(final RecyclerFactory recyclerFactory) {
      * @param message the message to make available again
      * @since 2.7
      */
-    @SuppressWarnings("deprecation")
+    @SuppressWarnings("removal")
     public static void release(final Message message) { // LOG4J2-1583
         if (message instanceof ReusableMessage) {
             ((ReusableMessage) message).clear();