code: protected static final void append(StringBuilder builder, String key, String value) {
  
  		// Convert key
  		String formattedKey = key.replace('[', '.').replace("]", "");
  
  		// Append key
  		char c;
  		boolean replace = false;
  		char[] chars = formattedKey.toCharArray();
  		for (int i = 0; i < chars.length; i++) {
  			c = chars[i];
  			if ((c > 0xFF) || KEY_ESCAPES[c] != 0) {
  				replace = true;
  				break;
  			}
  		}
  		if (replace) {
  			appendWithEscapes(builder, formattedKey, KEY_ESCAPES);
  		} else {
  			builder.append(formattedKey);
  		}
  		builder.append('=');
  
  		// Append value
  		if (value != null && !value.isEmpty()) {
  			replace = false;
  			chars = value.toCharArray();
  			for (int i = 0; i < chars.length; i++) {
  				c = chars[i];
  				if ((c > 0xFF) || VALUE_ESCAPES[c] != 0) {
  					replace = true;
  					break;
  				}
  			}
  			if (replace) {
  				appendWithEscapes(builder, value, VALUE_ESCAPES);
  			} else {
  				builder.append(value);
  			}
  		}
  
  		// Line break
  		builder.append(LINE_SEPARATOR);
  	}
docs: --- CHARACTER CONVERTERS ---