@JsonProperty("max_docs_per_index")
    public abstract int maxDocsPerIndex();
@Test
    public void testDeserialization() throws IOException {
        final ObjectMapper objectMapper = new ObjectMapperProvider().get();
        final String json = "{ \"type\": \"org.graylog2.indexer.rotation.strategies.MessageCountRotationStrategyConfig\", \"max_docs_per_index\": 1000 }";
        final RotationStrategyConfig config = objectMapper.readValue(json, RotationStrategyConfig.class);

        assertThat(config).isInstanceOf(MessageCountRotationStrategyConfig.class);
        assertThat(((MessageCountRotationStrategyConfig) config).maxDocsPerIndex()).isEqualTo(1000);
    }