code: public final void assertReady() throws ConfigurationException {
          ArrayList<String> messages = new ArrayList<String>();
          errorCheck(messages);
          int size = messages.size();
          if (size == 0) {
              return;
          }
          StringBuilder b = new StringBuilder();
          if (size > 1) {
              b.append("Multiple problems: ");
          }
          for (int i=0; i<size; i++) {
              if (i > 0) {
                  b.append("; ");
              }
              b.append(messages.get(i));
          }
          throw new ConfigurationException(b.toString());
      }
docs: Throw a configuration exception if the configuration is not filled out
  sufficiently and correctly such that a repository could be instantiated
  from it.