Trace Id not preserved when calling netflix FeignClient

Question

I am using spring-cloud-sleuth-zipkin and spring-cloud-starter-sleuth as dependency.

When i call a netflix FeignClient call TraceId changes...

import org.springframework.cloud.netflix.feign.FeignClient;

@FeignClient
public interface TesterClient {
@RequestLine("GET /testCall")
@Headers({"Authorization: Bearer {bearerToken}",
        "Content-Type: application/json"})
ResponseEntity<Test> testMethod(@Param("bearerToken") String bearerToken);
}

@Bean
public TesterClient testerClient() {
    return Feign.builder()
            .decoder(new TestDecoder()).encoder(new TestEncoder())
            .logLevel(Logger.Level.FULL).target(TesterClient.class, 
this.testUrl);
}

When i call TesterClient the traceId changes? How could i preserve the same traceId?