@Test void supportsCompression() {
    assertThat(getContentEncodingFromRequestThatAcceptsGzip("/zipkin/test.txt"))
      .isNull(); // too small to compress
    assertThat(getContentEncodingFromRequestThatAcceptsGzip("/zipkin/config.json"))
      .isEqualTo("gzip");
  }
Some assets are pretty big. ensure they use compression.
zipkin-server/src/test/java/zipkin2/server/internal/ui/ITZipkinUiConfiguration.java