protoc 21.7 not found

[qpl23]

I originally thought this was a typo, but it seems protoc 21.7 does exist. So, edit:

The build.gradle snippet in the web tutorial specifies:

  protoc {
        artifact = "com.google.protobuf:protoc:21.7"
    }

But Android Studio can't find protoc 21.7 with the provided repository setting:

    repositories {
        google()
        mavenCentral()
    }

giving the error:

> Could not resolve all files for configuration ':app:protobufToolsLocator_protoc'.
   > Could not find com.google.protobuf:protoc:21.7.
     Searched in the following locations:
       - https://dl.google.com/dl/android/maven2/com/google/protobuf/protoc/21.7/protoc-21.7.pom
       - https://repo.maven.apache.org/maven2/com/google/protobuf/protoc/21.7/protoc-21.7.pom
     Required by:
         project :app

Changing the protoc stanza to read artifact = "com.google.protobuf:protoc:3.21.7" (i.e. changing the version from 21.7 to 3.21.7) makes this problem go away.