[Java] Fix content for enum with restclient (#19973)

Author: jarryDk

.github/workflows/samples-java-client-jdk17.yaml

@@ -7,12 +7,14 @@ on:
       - samples/client/petstore/java/webclient-jakarta/**
       - samples/client/petstore/java/restclient-*/**
       - samples/client/petstore/java/webclient-useSingleRequestParameter/**
+      - samples/client/others/java/restclient-enum-in-multipart/**
   pull_request:
     paths:
       - samples/client/petstore/java/resttemplate-jakarta/**
       - samples/client/petstore/java/webclient-jakarta/**
       - samples/client/petstore/java/restclient-*/**
       - samples/client/petstore/java/webclient-useSingleRequestParameter/**
+      - samples/client/others/java/restclient-enum-in-multipart/**
 jobs:
   build:
     name: Build Java Client JDK17
@@ -30,6 +32,7 @@ jobs:
           - samples/client/petstore/java/restclient-useSingleRequestParameter
           - samples/client/petstore/java/restclient-useSingleRequestParameter-static
           - samples/client/petstore/java/webclient-useSingleRequestParameter
+          - samples/client/others/java/restclient-enum-in-multipart
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-java@v4