Do not using static finals for PID and format

Update SimpleFormatter so that the PID and format can be different per
formatter instance.

spring-bootstrap/src/main/java/org/springframework/bootstrap/logging/java/SimpleFormatter.java

@@ -31,11 +31,11 @@ public class SimpleFormatter extends Formatter {
 
 	private static final String DEFAULT_FORMAT = "[%1$tY-%1$tm-%1$td %1$tH:%1$tM:%1$tS.%1$tL] - %8$s %4$s [%7$s] --- %3$s: %5$s%6$s%n";
 
-	private static String FORMAT = setOrUseDefault("LOG_FORMAT", DEFAULT_FORMAT);
+	private final String format = getOrUseDefault("LOG_FORMAT", DEFAULT_FORMAT);
 
-	private final Date date = new Date();
+	private final String pid = getOrUseDefault("PID", "????");
 
-	private static String PID = setOrUseDefault("PID", "????");
+	private final Date date = new Date();
 
 	@Override
 	public synchronized String format(LogRecord record) {
@@ -44,8 +44,9 @@ public class SimpleFormatter extends Formatter {
 		String message = formatMessage(record);
 		String throwable = getThrowable(record);
 		String thread = getThreadName();
-		return String.format(FORMAT, this.date, source, record.getLoggerName(), record
+		return String.format(this.format, this.date, source, record.getLoggerName(),
-				.getLevel().getLocalizedName(), message, throwable, thread, PID);
+				record.getLevel().getLocalizedName(), message, throwable, thread,
+				this.pid);
 	}
 
 	private String getThrowable(LogRecord record) {
@@ -65,7 +66,7 @@ public class SimpleFormatter extends Formatter {
 		return (name == null ? "" : name);
 	}
 
-	private static String setOrUseDefault(String key, String defaultValue) {
+	private static String getOrUseDefault(String key, String defaultValue) {
 		String value = null;
 		try {
 			value = System.getenv(key);