code: private static String getPackageName(Class<?> clazz) {
  
          LettuceAssert.notNull(clazz, "Class must not be null");
          return getPackageName(clazz.getName());
      }
docs: Determine the name of the package of the given class, e.g. "java.lang" for the {@code java.lang.String} class.
  
  @param clazz the class
  @return the package name, or the empty String if the class is defined in the default package