Inorder to make Javabench work with HTTPS, you need to follow the below given steps
First extract the cert from the client-truststore of ESB
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keytool -export -alias wso2carbon -file wso2carbon.crt -keystore client-truststore.jks
Then import the wso2esb.crt to java's cacert
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keytool -import -alias wso2carbon -file "/home/ESB/3.0.1/wso2esb-3.0.1/resources/security/wso2carbon.crt" -keystore /opt/software/java/SUN_JDK-1.6/jdk1.6.0_21/jre/lib/security/cacerts