code: protected Boolean getBooleanParam(String paramName, String errorMessage, Map<String, Object> mapToUse) throws IOException {
          Boolean result = getTypedParam(paramName, errorMessage, Boolean.class, mapToUse);
          if (result == null) {
              String s = getTypedParam(paramName, errorMessage, String.class, mapToUse);
              if (s != null) {
                  return Boolean.parseBoolean(s);
              }
          }
          return result;
      }
docs: Convenience method for subclasses.
  
  @param paramName    the name of the parameter
  @param errorMessage the errormessage to add to the exception if the param does not exist.
  @param mapToUse     The map to use as inputsource for parameters. Should not be null.
  @return a stringparameter with given name. If it does not exist and the errormessage is provided,
  an IOException is thrown with that message. if the errormessage is not provided, null is returned.
  @throws IOException Exception if the paramname does not exist and an errormessage is provided.