private static void appendTag(String tag, StringBuilder buffer) {
        if (buffer.length() != 0) {
            buffer.append(UNDERSCORE);
        }

        buffer.append(tag);
    }
private static void appendTag ( String tag , StringBuilder buffer ) { if ( buffer . length ( ) != 0 ) { buffer . append ( UNDERSCORE ) ; } buffer . append ( tag ) ; }
Append a tag to a StringBuilder, adding the separator if necessary.The tag must
not be a zero-length string.

@param tag The tag to add.
@param buffer The output buffer.