[java][doc] Fix Makdown examples: wrong collection type used to initialize Sets #903

Job	Run time
Build Java Client JDK17 (samples/client/petstore/java/restclient)	2m 14s
Build Java Client JDK17 (samples/client/petstore/java/restclient-springBoot4-jackson3)	1m 43s
Build Java Client JDK17 (samples/client/petstore/java/restclient-springBoot4-jackson2)	1m 35s
Build Java Client JDK17 (samples/client/petstore/java/restclient-nullable-arrays)	1m 48s
Build Java Client JDK17 (samples/client/petstore/java/webclient-jakarta)	1m 34s
Build Java Client JDK17 (samples/client/others/java/webclient-sealedInterface_3_1)	1m 53s
Build Java Client JDK17 (samples/client/petstore/java/restclient-swagger2)	2m 6s
Build Java Client JDK17 (samples/client/petstore/java/resttemplate-jakarta)	1m 41s
Build Java Client JDK17 (samples/client/petstore/java/restclient-useSingleRequestParameter-static)	2m 12s
Build Java Client JDK17 (samples/client/petstore/java/webclient-useSingleRequestParameter)	1m 46s
Build Java Client JDK17 (samples/client/others/java/webclient-sealedInterface)	1m 50s
Build Java Client JDK17 (samples/client/others/java/restclient-enum-in-multipart)	1m 38s
Build Java Client JDK17 (samples/client/petstore/java/restclient-useSingleRequestParameter)	2m 14s
	24m 14s

Provide feedback