fix deprecated old sbt build file syntax #884

Job	Run time
Build Java Client JDK8 (samples/client/echo_api/java/resttemplate)	1m 6s
Build Java Client JDK8 (samples/client/echo_api/java/feign-gson)	51s
Build Java Client JDK8 (samples/client/echo_api/java/resteasy)	51s
Build Java Client JDK8 (samples/client/echo_api/java/okhttp-gson)	1m 2s
Build Java Client JDK8 (samples/client/echo_api/java/apache-httpclient)	1m 12s
	5m 2s

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