public Set<MapperConfig> load(InputStream inputStream) throws IOException {
        final PrometheusMappingConfig config = ymlMapper.readValue(inputStream, PrometheusMappingConfig.class);

        return config.metricMappingConfigs()
                .stream()
                .flatMap(this::mapMetric)
                .collect(Collectors.toSet());
    }
@Test
    void defaultType() throws Exception {

        final Map<String, ImmutableList<Serializable>> config = Collections.singletonMap("metric_mappings",
                ImmutableList.of(
                        ImmutableMap.of("metric_name", "test1", "match_pattern", "foo.bar")));

        assertThat(configLoader.load(new ByteArrayInputStream(objectMapper.writeValueAsBytes(config))))
                .containsExactlyInAnyOrder(new MapperConfig(
                        "foo.bar",
                        "gl_test1",
                        ImmutableMap.of("node", "5ca1ab1e-0000-4000-a000-000000000000")));
    }