feat(java): Generate servers for restclient library (#21699) #1256

Job	Run time
Build Java Client JDK11 (samples/client/echo_api/java/feign-gson)	1m 5s
Build Java Client JDK11 (samples/client/echo_api/java/apache-httpclient)	1m 12s
Build Java Client JDK11 (samples/client/echo_api/java/resteasy)	59s
Build Java Client JDK11 (samples/client/echo_api/java/native)	1m 32s
Build Java Client JDK11 (samples/client/echo_api/java/resttemplate)	1m 14s
	6m 2s

Provide feedback