As per the code https://github.com/igniterealtime/Smack/blob/master/smack-bosh/src/main/java/org /jivesoftware/smack/bosh/XMPPBOSHConnect…
after line 151 there should be cfgBuilder.setCompressionEnabled(config.isCompressionEnabled());
which is missing, I think jbosh already supports compression