code: @SuppressWarnings("unchecked")
      public <T> T get(final Object key, final T defaultValue) {
          notNull("defaultValue", defaultValue);
          Object value = documentAsMap.get(key);
          return value == null ? defaultValue : (T) value;
      }
docs: Gets the value of the given key, casting it to {@code Class<T>} or returning the default value if null.
  This is useful to avoid having casts in client code, though the effect is the same.
  
  @param key   the key
  @param defaultValue what to return if the value is null
  @param <T>   the type of the class
  @return the value of the given key, or null if the instance does not contain this key.
  @throws ClassCastException if the value of the given key is not of type T
  @since 3.5