Remove deprecated Configuration.setVisible(boolean) calls (Gradle 9.8)

[breskeby]

Problem

Gradle 9.8.0-milestone-2 deprecates Configuration.setVisible(boolean) (scheduled for removal in Gradle 11). The protobuf-gradle-plugin sets visible = false on three internal configurations, so any build that treats deprecations as errors (org.gradle.warning.mode=fail) fails as soon as the plugin is applied:

The Configuration.setVisible(boolean) method has been deprecated. This is
scheduled to be removed in Gradle 11.
  ...
  at com.google.protobuf.gradle.ProtobufPlugin...

See the Gradle 9.8 upgrade guide: #deprecate-visible-property.

Fix

Guard the visible = false calls behind a Gradle version check on the three internal configurations:

• protobufToolsLocator_* (ToolsLocator)
• the per-source-set protobuf configuration (ProtobufPlugin)
• compileProtoPath (ProtobufPlugin)

if (GradleVersion.current() < GradleVersion.version('9.8')) {
  it.visible = false
}

On Gradle 9.8+ the visible property is deprecated and inert, so it is skipped to stay warning-clean. On older Gradle versions the original visible = false behaviour is preserved, keeping these internal configurations out of certain reports/publications.

Context

Surfaced while testing Gradle 9.8.0-milestone-2 against Elasticsearch, which runs with org.gradle.warning.mode=fail. The deprecation was a hard build blocker for projects such as :x-pack:plugin:otel-data that apply this plugin.