Removed unnecessary cast to HttpClientErrorException as both classes … #1056

Job	Run time
Build Java Client JDK8 (samples/client/echo_api/java/resteasy)	1m 26s
Build Java Client JDK8 (samples/client/echo_api/java/feign-gson)	1m 42s
Build Java Client JDK8 (samples/client/echo_api/java/apache-httpclient)	1m 41s
Build Java Client JDK8 (samples/client/echo_api/java/okhttp-gson)	1m 34s
Build Java Client JDK8 (samples/client/echo_api/java/resttemplate)	1m 38s
	8m 1s

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