code: public String getNextStringParam(InputStream in, String strName, Map<String, Object> properties)
      {
          String string = null;
          if (properties != null)
              if (properties.get(strName) != null)
                  string = properties.get(strName).toString();
          if (NULL.equals(string))
              string = null;
          return string;
      }
docs: Get the next (String) param.
  Typically this is overidden in the concrete implementation.
  @param strName The param name (in most implementations this is optional).
  @param properties The temporary remote session properties
  @return The next param as a string.