code: public static Excerpt checkState(
        String conditionTemplate,
        String messageTemplate,
        Object... args) {
      return new GuavaCheckExcerpt(
          "checkState", conditionTemplate, messageTemplate, args, IllegalStateException.class);
    }
docs: Returns an excerpt equivalent to Guava's
  {@link Preconditions#checkState(boolean, String, Object...)}.
  <ul>
  <li>If Guava is available, Preconditions.checkState will be used.
  <li>Otherwise, the check will be done with an if block.
  </ul>
  
  <pre>code.add(checkState("%1$s &lt; %2$s",
  "start must be before end (got %1$s and %2$s)", "start", "end"));</pre>
  
  @param condition an excerpt containing the expression to pass to the checkState method
  @param message the error message template to pass to the checkState method
  @param args excerpts containing the error message arguments to pass to the checkState method