code: private JavaClass checkClass() {
      // TODO(peleyal): check if caching the beta state of every class could improve
      // performance on large projects
  
      try {
        JavaClass javaClass = Repository.lookupClass(getClassConstantOperand());
        boolean isGoogleClass = javaClass.getClassName().startsWith("com.google.api.client");
        if (!isGoogleClass) {
          return null;
        }
  
        // suppress errors when declaring fields inside a class (e.g. declaration of Beta
        // field in Beta class)
        if (javaClass.getClassName().equals(getDottedClassName())) {
          return null;
        }
  
        // suppress errors if the container class or method is beta
        if (isBeta(getThisClass().getAnnotationEntries())
            || (getMethod() != null && isBeta(getMethod().getAnnotationEntries()))) {
          return null;
        }
  
        if (isBeta(javaClass.getAnnotationEntries())) {
          bugReporter.reportBug(createBugInstance(BETA_CLASS_USAGE).addClass(javaClass));
          return null;
        }
  
        return javaClass;
      } catch (ClassNotFoundException e) {
        bugReporter.reportMissingClass(e);
        return null;
      }
    }
docs: Returns {@link JavaClass} for the current operand only if it's a Google APIs Client library
  class, it's not {@link Beta} and it doesn't appear in other {@link Beta} section. Otherwise
  returns {@code null}.
  
  <p>Reports a bug in case the class is {@link Beta}.