Remove StringBuilder in Logback TimestampConverter (#97)

* Changed from StringBuilder to String

Since we are appending only once, String.valueOf(timestamp) will suffice.

Author: rahuldeepattri

cf-java-logging-support-logback/src/main/java/com/sap/hcp/cf/logback/converter/TimestampConverter.java

@@ -16,11 +16,9 @@ public class TimestampConverter extends ClassicConverter {
 
     @Override
     public String convert(ILoggingEvent event) {
-        StringBuilder appendTo = new StringBuilder();
-		Instant now = Instant.now();
-		long timestamp = now.getEpochSecond() * 1_000_000_000L + now.getNano();
-		appendTo.append(timestamp);
-        return appendTo.toString();
+        Instant now = Instant.now();
+        long timestamp = now.getEpochSecond() * 1_000_000_000L + now.getNano();
+        return String.valueOf(timestamp);
     }
 
     @Override