The option appears to do nothing. This is in Astyle v3.1 on Fedora 28
Example 1 Original:
public String foo(String bar) { return ("test"); }
Result:
public String foo(String bar) { return ("test"); }
Example 2 Original:
public String foo(String bar) { return ("test"); }
Result:
public String foo(String bar) { return ("test"); }