@Test void ignoresEmptyURL() {
    ZipkinActiveMQCollectorProperties properties = new ZipkinActiveMQCollectorProperties();
    properties.setUrl("");

    assertThat(properties.getUrl()).isNull();
  }
This prevents an empty ACTIVEMQ_URL variable from being mistaken as a real one
zipkin-server/src/test/java/zipkin2/server/internal/activemq/ZipkinActiveMQCollectorPropertiesTest.java