I can't get scalafmt working through rules_scala_annex

.gitignore

bazel-*

.scalafmt.conf

maxColumn = 120
align = none
newlines.alwaysBeforeElseAfterCurlyIf = true
binPack.literalArgumentLists = false
rewrite.rules = [SortImports]

BUILD

load("@rules_scala_annex//rules:scala.bzl", "scala_library", "scala_binary", "scala_test")
load("@rules_scala_annex//rules:scalafmt.bzl", "scala_format_test")

scala_binary(
    name="binary",
    srcs=["Hello.scala"],
    main_class="com.onzo.Hello",
)

scala_format_test(
    name = "format",
    srcs = glob(["**/*.scala"]),
)

Hello.scala

package com.onzo

object Hello
{
def main(args: Array[String])
: Unit
=
println(
"I'm a very badly-formatted Scala program"
)
}

WORKSPACE

# proto_library, cc_proto_library, and java_proto_library rules implicitly
# depend on @com_google_protobuf for protoc and proto runtimes.
# This statement defines the @com_google_protobuf repo.
http_archive(
    name = "com_google_protobuf",
    sha256 = "cef7f1b5a7c5fba672bec2a319246e8feba471f04dcebfe362d55930ee7c1c30",
    strip_prefix = "protobuf-3.5.0",
    urls = ["https://github.com/google/protobuf/archive/v3.5.0.zip"],
)


rules_scala_annex_commit = "b80e278392e264ec62aeedc44edd9b7fd19a9ce8"
rules_scala_annex_sha256 = "987d5907f2182fea677a5945ed733dd31edd892748f4b8c28e6d1b48889f316b"

http_archive(
  name = "rules_scala_annex",
  sha256 = rules_scala_annex_sha256,
  strip_prefix = "rules_scala_annex-%s" % rules_scala_annex_commit,
  url = "https://github.com/andyscott/rules_scala_annex/archive/%s.zip" % rules_scala_annex_commit,
)

load("@rules_scala_annex//rules/scala:workspace.bzl", "scala_register_toolchains", "scala_repository", "scala_repositories")

scala_repositories()
scala_register_toolchains()

scala_repository("scala", ("org.scala-lang", "2.12.7"), "@compiler_bridge_2_12//:src")

load("@rules_scala_annex//rules/scalafmt:workspace.bzl", "scalafmt_default_config", "scalafmt_repositories")
scalafmt_repositories()
scalafmt_default_config()