I don't see your point. If you have a collection of source files, then something must search the directory tree to find them and feed them to the compiler ... ideally, only the files that have changed, to give fast incremental compilation.
If you use a typical Java IDE like IntelliJ then the program that does that will be the IDE. There is no "one more layer" because that's the first and only layer.
If the IDE build system does not provide enough features or you'd like your codebase to be IDE independent, you can also use a separate build tool, or a combination of both (in which case the IDE will sync itself to the other build tool).
In that case there are two layers. But Go does not have any magical solution to that. There will be Go apps that need more than the little command line tool can do as well.
Right, so then it is more complex than `go build`. QED.
To be clear, I'm not claiming that Go is "better"; I'm just pointing out that this is why one would chose Go over Java. Sometimes this particular benefit doesn't outweigh the costs relative to developing in Java, but language/toolchain simplicity remains -- nonetheless -- the reason why people prefer one over the other.
Yes, "gradle build" wants to see a "build.gradle" file in the current directory, but you can run "gradle init" to get one. And after that everything except specifying dependencies is by convention.
There's really little to no difference in complexity here. What Go saves by not having a build file it loses by not encoding enough information about dependencies in the source, which leads to horrible hacks like vendoring.
If you use a typical Java IDE like IntelliJ then the program that does that will be the IDE. There is no "one more layer" because that's the first and only layer.
If the IDE build system does not provide enough features or you'd like your codebase to be IDE independent, you can also use a separate build tool, or a combination of both (in which case the IDE will sync itself to the other build tool).
In that case there are two layers. But Go does not have any magical solution to that. There will be Go apps that need more than the little command line tool can do as well.