URIBuilder in 5.1 encodes more characters than necessary

Take this simple code example:

System.out.println(new URIBuilder().setScheme("https").setHost("example.com").setPathSegments("foo:bar").toString());

In 5.0 and in 4.x, this code would produce 

https://example.com/foo:bar

Since 5.1, the behavior has changed. It now produces

https://example.com/foo%3Abar

This actually broke one of my calls to iap.googleapis.com. I know it can be argued that it's the server's fault for not decoding %3A, but ':' does not actually need to be encoded in URL path segments. Also, this is an unnecessary breaking change in URIBuilder's behavior.