code: private void initSupportedExtensions(SMTPClientSession session, SMTPResponse response) {
          Iterator<String> lines = response.getLines().iterator();
          while(lines.hasNext()) {
              String line = lines.next();
              if (line.equalsIgnoreCase(PIPELINING_EXTENSION)) {
                  session.addSupportedExtensions(PIPELINING_EXTENSION);
              } else if (line.equalsIgnoreCase(STARTTLS_EXTENSION)) {
                  session.addSupportedExtensions(STARTTLS_EXTENSION);
              }
          }
      }
docs: Return all supported extensions which are included in the {@link SMTPResponse}
  
  @param response
  @return extensions