private static boolean notFalse(String s) {
      return s == null || !s.equals("false");
    }
This condition passes when "zipkin.discovery.eureka.url" is set to non-empty.

<p>This is here because the yaml defaults this property to empty like this, and spring-boot
doesn't have an option to treat empty properties as unset.

<pre>{@code
url: ${EUREKA_URL:}
}</pre>
zipkin-server/src/main/java/zipkin2/server/internal/eureka/ZipkinEurekaDiscoveryConfiguration.java