APIGee Callout: Socket/HTTP communication to local endpoint

[SachinDesai]

While i see that socket communication to local/sitelocal/link local arent allowed, higher level functions like Javascript/Java based httpclient.send() is allowed in callouts. 

Is this an expected behavior for Javascript/Java or will this change in future? Also, was curious about why one is allowed over other?

Thanks in advance

[SachinDesai]

Update:

Javascript httpclient call accepts 10.x.x.x endpoints while Java's 

HttpClientBuilder() doesnt. Is this expected?