openfegin一個小問題 Illegal character in path at index

使用openfeign遇到一個簡單錯誤：

Caused by: java.net.URISyntaxException: Illegal character in path at index 32: http://test-service/v1/tests/py/{pid}
    at java.net.URI$Parser.fail(URI.java:2848) ~[?:1.8.0_181]
    at java.net.URI$Parser.checkChars(URI.java:3021) ~[?:1.8.0_181]
    at java.net.URI$Parser.parseHierarchical(URI.java:3105) ~[?:1.8.0_181]
    at java.net.URI$Parser.parse(URI.java:3053) ~[?:1.8.0_181]
    at java.net.URI.<init>(URI.java:588) ~[?:1.8.0_181]
    at java.net.URI.create(URI.java:850) ~[?:1.8.0_181]
    at org.springframework.cloud.openfeign.ribbon.LoadBalancerFeignClient.execute(LoadBalancerFeignClient.java:56) ~[spring-cloud-openfeign-core-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.cloud.sleuth.instrument.web.client.feign.TraceLoadBalancerFeignClient.execute(TraceLoadBalancerFeignClient.java:67) ~[spring-cloud-sleuth-core-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:98) ~[feign-core-9.7.0.jar:?]
    at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:77) ~[feign-core-9.7.0.jar:?]

從錯誤上看，這只是一個非法的url形成的，可是實際檢查發現，根本緣由不是這個，我有一個commonservice須要調用testservice，調用代碼：

@GetMapping(value= "v1/tests/py/{pid}")
    Message<List<PPyVO>> getPPy(@PathVariable("pid") Long pid);

發現調用這個接口的時候，傳遞的參數是null，原來我認爲就算是null也應該把{pid}給替換掉，可是實際上並不會，因此產生了這個問題。