Use DateTimeFormatter.formatTo to directly append to StringBuilder

Author: michaelbraun

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

@@ -459,7 +459,7 @@ private static boolean appendDate(final Object o, final StringBuilder str) {
         if (!(o instanceof Date)) {
             return false;
         }
-        str.append(DATE_FORMATTER.format(((Date) o).toInstant()));
+        DATE_FORMATTER.formatTo(((Date) o).toInstant(), str);
         return true;
     }
 

log4j-api/src/main/java/org/apache/logging/log4j/status/StatusData.java

@@ -167,9 +167,9 @@ public Throwable getThrowable() {
     @SuppressWarnings("DefaultCharset")
     public String getFormattedStatus() {
         final StringBuilder sb = new StringBuilder();
-        final String formattedInstant =
-                instantFormatter != null ? instantFormatter.format(instant) : instant.toString();
-        sb.append(formattedInstant);
+        // DateTimeFormatter.ISO_INSTANT is the default used in instant.toString()
+        DateTimeFormatter formatterToUse = instantFormatter != null ? instantFormatter : DateTimeFormatter.ISO_INSTANT;
+        formatterToUse.formatTo(instant, sb);
         sb.append(SPACE);
         sb.append(getThreadName());
         sb.append(SPACE);