code: public static <K, V> MapAssert<K, V> assertThat(Map<K, V> collection) {
          return new MapAssert<>(collection);
      }
docs: Creates an instance of {@link MapAssert}.
  
  @param collection the value to be asserted
  @param <K>        type of key
  @param <V>        type of value
  @return instance of assertion object