code: public String replaceFirstRegex(String subject, 
                                      String regex, String replacement) {
          return subject.replaceFirst(regex, replacement);
      }
docs: Replace the given regular expression pattern with the given replacement.
  Only the first match will be replaced.
  
  @param subject The value to replace
  @param regex The regular expression pattern to match
  @param replacement The replacement value
  
  @return A new string based on the replacement of the expression
  
  @see String#replaceFirst(String, String)