in java/src/main/java/com/twitter/twittertext/Autolink.java [179:197]
public void linkToTextWithSymbol(Entity entity, CharSequence symbol, CharSequence originalText,
Map<String, String> attributes, StringBuilder builder) {
final CharSequence taggedSymbol = symbolTag == null || symbolTag.length() == 0 ? symbol :
String.format("<%s>%s</%s>", symbolTag, symbol, symbolTag);
final CharSequence text = escapeHTML(originalText);
final CharSequence taggedText = textWithSymbolTag == null ||
textWithSymbolTag.length() == 0 ? text :
String.format("<%s>%s</%s>", textWithSymbolTag, text, textWithSymbolTag);
final boolean includeSymbol =
usernameIncludeSymbol || !Regex.AT_SIGNS.matcher(symbol).matches();
if (includeSymbol) {
linkToText(entity, taggedSymbol.toString() + taggedText, attributes, builder);
} else {
builder.append(taggedSymbol);
linkToText(entity, taggedText, attributes, builder);
}
}