Program: 163308
Project: 163308
Buggy source:
private boolean append(boolean isElementQuoted,String element){
  if (element == null) {
    if (nullValue == null) {
      return isElementQuoted;
    }
    element=nullValue;
  }
  int start=0;
  if (this.ignoreLeading) {
    start=skipLeadingWhitespace(element);
  }
  final int length=element.length();
  if (start < length && element.charAt(start) == quoteChar) {
    isElementQuoted=true;
  }
  if (isElementQuoted) {
    if (usingNullOrEmptyValue && length >= 2) {
      isElementQuoted=!(element.charAt(0) == quoteChar && element.charAt(length - 1) == quoteChar);
      if (isElementQuoted) {
        appendQuoted(start,element);
        return true;
      }
    }
 else {
      appendQuoted(start,element);
      return true;
    }
  }
  int i=start;
  char ch='\0';
  for (; i < length; i++) {
    ch=element.charAt(i);
    if (ch == quoteChar || ch == separator || ch == newLine || ch == escapeChar || (ch < maxTrigger && quotationTriggers[ch])) {
      appender.append(element,start,i);
      start=i + 1;
      if (ch == quoteChar) {
        if (quoteElement(i,element)) {
          appendQuoted(i,element);
          return true;
        }
 else         if (escapeUnquoted) {
          appendQuoted(i,element);
        }
 else {
          appender.append(element,i,length);
          if (ignoreTrailing && element.charAt(length - 1) <= ' ') {
            appender.updateWhitespace();
          }
        }
        return isElementQuoted;
      }
 else       if (ch == escapeChar && inputNotEscaped && escapeEscape != '\0' && escapeUnquoted) {
        appender.append(escapeEscape);
      }
 else       if (ch == separator || ch == newLine || ch < maxTrigger && quotationTriggers[ch]) {
        appendQuoted(i,element);
        return true;
      }
      appender.append(ch);
    }
  }
  appender.append(element,start,i);
  if (ch <= ' ' && this.ignoreTrailing) {
    appender.updateWhitespace();
  }
  return isElementQuoted;
}

Fixed version (ground truth):
private boolean append(boolean isElementQuoted,String element){
  if (element == null) {
    if (nullValue == null) {
      return isElementQuoted;
    }
    element=nullValue;
  }
  int start=0;
  if (this.ignoreLeading) {
    start=skipLeadingWhitespace(element);
  }
  final int length=element.length();
  if (start < length && element.charAt(start) == quoteChar) {
    isElementQuoted=true;
  }
  if (isElementQuoted) {
    if (usingNullOrEmptyValue && length >= 2) {
      if (element.charAt(0) == quoteChar && element.charAt(length - 1) == quoteChar) {
        appender.append(element);
        return false;
      }
 else {
        appendQuoted(start,element);
        return true;
      }
    }
 else {
      appendQuoted(start,element);
      return true;
    }
  }
  int i=start;
  char ch='\0';
  for (; i < length; i++) {
    ch=element.charAt(i);
    if (ch == quoteChar || ch == separator || ch == newLine || ch == escapeChar || (ch < maxTrigger && quotationTriggers[ch])) {
      appender.append(element,start,i);
      start=i + 1;
      if (ch == quoteChar) {
        if (quoteElement(i,element)) {
          appendQuoted(i,element);
          return true;
        }
 else         if (escapeUnquoted) {
          appendQuoted(i,element);
        }
 else {
          appender.append(element,i,length);
          if (ignoreTrailing && element.charAt(length - 1) <= ' ') {
            appender.updateWhitespace();
          }
        }
        return isElementQuoted;
      }
 else       if (ch == escapeChar && inputNotEscaped && escapeEscape != '\0' && escapeUnquoted) {
        appender.append(escapeEscape);
      }
 else       if (ch == separator || ch == newLine || ch < maxTrigger && quotationTriggers[ch]) {
        appendQuoted(i,element);
        return true;
      }
      appender.append(ch);
    }
  }
  appender.append(element,start,i);
  if (ch <= ' ' && this.ignoreTrailing) {
    appender.updateWhitespace();
  }
  return isElementQuoted;
}