Custom User-Agent header not working

Hi,

 

I hope someone can help with this, I'm using SoapUI 5.40 to run some REST API tests and I'm trying to authenticate using OAuth2 and I need to modify the default User-Agent header when requesting the Access Token. I have changed the default value from Preferences > HTTP Settings, however when I make the request, the header is still using the same default value "Apache..".

 

I've also tried to add the value manually from the Headers tab, which it didn't make any difference.

 

Any ideas how I can modify the User-Agent header or why is not applying the customed value?

 

Logs:

Thu Sep 20 14:23:26 BST 2018:DEBUG:>> "Content-Type: application/x-www-form-urlencoded[\r][\n]"
Thu Sep 20 14:23:26 BST 2018:DEBUG:>> "Content-Length: 145[\r][\n]"
Thu Sep 20 14:23:26 BST 2018:DEBUG:>> "Connection: Keep-Alive[\r][\n]"
Thu Sep 20 14:23:26 BST 2018:DEBUG:>> "User-Agent: Apache-HttpClient/4.1.1 (java 1.5)[\r][\n]"

 

Preferences: