Program: 90434
Project: 90434
Buggy source:
/** 
 * Constructor.
 * @param loggerName The name of the Logger.
 * @param marker The Marker or null.
 * @param loggerFQCN The fully qualified class name of the caller.
 * @param level The logging Level.
 * @param message The Message.
 * @param thrown A Throwable or null.
 * @param thrownProxy A ThrowableProxy or null.
 * @param contextData The key-value pairs from the context.
 * @param contextStack the nested diagnostic context.
 * @param threadId the thread ID
 * @param threadName The name of the thread.
 * @param threadPriority the thread priority
 * @param source The locations of the caller.
 * @param timestampMillis The timestamp of the event.
 * @param nanoOfMillisecond the nanoseconds within the millisecond, always positive, never exceeds {@code 999,999}
 * @param nanoTime The value of the running Java Virtual Machine's high-resolution time source when the event wascreated.
 */
private Log4jLogEvent(final String loggerName,final Marker marker,final String loggerFQCN,final Level level,final Message message,final Throwable thrown,final ThrowableProxy thrownProxy,final StringMap contextData,final ThreadContext.ContextStack contextStack,final long threadId,final String threadName,final int threadPriority,final StackTraceElement source,final long timestampMillis,final int nanoOfMillisecond,final long nanoTime){
  this.loggerName=loggerName;
  this.marker=marker;
  this.loggerFqcn=loggerFQCN;
  this.level=level == null ? Level.OFF : level;
  this.message=message;
  this.thrown=thrown;
  this.thrownProxy=thrownProxy;
  this.contextData=contextData == null ? ContextDataFactory.createContextData() : contextData;
  this.contextStack=contextStack == null ? ThreadContext.EMPTY_STACK : contextStack;
  long millis=message instanceof TimestampMessage ? ((TimestampMessage)message).getTimestamp() : timestampMillis;
  this.instant.initFromEpochMilli(millis,nanoOfMillisecond);
  this.threadId=threadId;
  this.threadName=threadName;
  this.threadPriority=threadPriority;
  this.source=source;
  if (message != null && message instanceof LoggerNameAwareMessage) {
    ((LoggerNameAwareMessage)message).setLoggerName(loggerName);
  }
  this.nanoTime=nanoTime;
}

Fixed version (ground truth):
private Log4jLogEvent(final String loggerName,final Marker marker,final String loggerFQCN,final Level level,final Message message,final Throwable thrown,final ThrowableProxy thrownProxy,final StringMap contextData,final ThreadContext.ContextStack contextStack,final long threadId,final String threadName,final int threadPriority,final StackTraceElement source,final long nanoTime){
  this.loggerName=loggerName;
  this.marker=marker;
  this.loggerFqcn=loggerFQCN;
  this.level=level == null ? Level.OFF : level;
  this.message=message;
  this.thrown=thrown;
  this.thrownProxy=thrownProxy;
  this.contextData=contextData == null ? ContextDataFactory.createContextData() : contextData;
  this.contextStack=contextStack == null ? ThreadContext.EMPTY_STACK : contextStack;
  this.threadId=threadId;
  this.threadName=threadName;
  this.threadPriority=threadPriority;
  this.source=source;
  if (message instanceof LoggerNameAwareMessage) {
    ((LoggerNameAwareMessage)message).setLoggerName(loggerName);
  }
  this.nanoTime=nanoTime;
}