I'm not sure a tool could do 100% translation but I'm sure it could do a lot.
A surprisingly large amount of time was just moving the order of variable declaration from Java's "type name" to Go's "name type" and renaming, say, "String" to "string".
If a tool did that for me, it would save a ton of time.
Unfortunately, the upfront time investment to learn enough to write even the simplest translator would probably be greater than time saved on one project.