Review feedback.

Author: stuhood

3rdparty/jvm/com/google/guava/BUILD

@@ -2,7 +2,9 @@ jvm_artifact(
     group="com.google.guava",
     artifact="guava",
     version="31.0.1-jre",
-    # Because `guava` provides a package which does not match its `group`, we explicitly list it here,
-    # which allows inference to recognize that imports of this package are provided by this artifact.
+    # Because `guava` provides a package which does not match its `group`, we explicitly list it
+    # here, which allows inference to recognize that imports of this package are provided by this
+    # artifact. See https://www.pantsbuild.org/v2.9/docs/reference-jvm_artifact#codepackagescode
+    # for more information.
     packages=["com.google.common.**"],
 )

3rdparty/jvm/com/lihaoyi/BUILD

@@ -3,5 +3,9 @@ jvm_artifact(
     group="com.lihaoyi",
     artifact="acyclic_2.13",
     version="0.2.1",
+    # Because `acyclic` provides a package which does not match its `group`, we explicitly list it
+    # here, which allows inference to recognize that imports of this package are provided by this
+    # artifact. See https://www.pantsbuild.org/v2.9/docs/reference-jvm_artifact#codepackagescode
+    # for more information.
     packages=["acyclic.**"],
 )

README.md

@@ -7,6 +7,11 @@ See the first
 for some unique
 benefits Pants brings to Java and Scala projects.
 
+This repository demonstrates a mix of Java and Scala, which is a common use case. But the Java
+and Scala backends can be independently enabled, so there is no need to expose Scala BUILD file
+symbols if you have a pure-Java repository. See comments in the `backends` section of
+[`pants.toml`](./pants.toml).
+
 This is only one possible way of laying out your project with Pants. See 
 [pantsbuild.org/docs/source-roots#examples](https://www.pantsbuild.org/docs/source-roots#examples) 
 for some other example layouts.

pants.toml

@@ -2,12 +2,18 @@
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
 [GLOBAL]
-pants_version = "2.9.0rc0"
+pants_version = "2.9.0rc1"
 backend_packages = [
-  "pants.backend.experimental.scala",
-  "pants.backend.experimental.scala.lint.scalafmt",
+  # This repository demonstrates a mix of Java and Scala, and so both backends are enabled. But each
+  # backend can be used independently, so there is no need to expose Scala BUILD file
+  # symbols if you have a pure-Java repository.
+  #
+  # Linters/formatters are also hosted in independent backends, to allow them to be independently
+  # enabled.
   "pants.backend.experimental.java",
   "pants.backend.experimental.java.lint.google_java_format",
+  "pants.backend.experimental.scala",
+  "pants.backend.experimental.scala.lint.scalafmt",
 ]
 
 [javac]