### Question:
ApmServerConfigurationSource extends AbstractConfigurationSource implements LifecycleListener { @Nullable static Integer parseMaxAge(@Nullable String cacheControlHeader) { if (cacheControlHeader == null) { return null; } Matcher matcher = MAX_AGE.matcher(cacheControlHeader); if (!matcher.find()) { return null; } return Integer.parseInt(matcher.group(1)); } ApmServerConfigurationSource(PayloadSerializer payloadSerializer, MetaData metaData, ApmServerClient apmServerClient);   ApmServerConfigurationSource(PayloadSerializer payloadSerializer, MetaData metaData, ApmServerClient apmServerClient, Logger logger); @Override void reload(); @Override void init(ElasticApmTracer tracer); @Override void start(final ElasticApmTracer tracer); @Override String getValue(String key); @Override String getName(); @Override void pause(); @Override void resume(); @Override void stop();  }### Answer:
@Test public void parseMaxAgeFromCacheControlHeader() { assertThat(ApmServerConfigurationSource.parseMaxAge("max-age=1")).isEqualTo(1); assertThat(ApmServerConfigurationSource.parseMaxAge("max-age= 1")).isEqualTo(1); assertThat(ApmServerConfigurationSource.parseMaxAge("max-age =1")).isEqualTo(1); assertThat(ApmServerConfigurationSource.parseMaxAge("max-age = 1")).isEqualTo(1); assertThat(ApmServerConfigurationSource.parseMaxAge("public, max-age = 42")).isEqualTo(42); assertThat(ApmServerConfigurationSource.parseMaxAge("max-age= 42 , public")).isEqualTo(42); assertThat(ApmServerConfigurationSource.parseMaxAge("public")).isNull(); assertThat(ApmServerConfigurationSource.parseMaxAge(null)).isNull(); }