Add open-source 'basic' cache provider and revamp licensing documentation (#930)

## Summary

- **New `basic` cache provider**: Adds an open-source (MIT-licensed)
caching implementation built on `@actions/cache` as an alternative to
the proprietary Enhanced Caching. Users can opt in with `cache-provider:
basic` on both `setup-gradle` and `dependency-submission` actions.
- **Revamped licensing & distribution docs**: Replaces the verbose
licensing notice block (previously shown in README, docs, and logs) with
a friendlier callout and a new dedicated
[DISTRIBUTION.md](./DISTRIBUTION.md) covering component licensing, usage
tiers, data privacy ("Safe Harbor"), and opt-out instructions.
- **Improved messaging**: Enhanced Caching and Basic Caching each
display concise, informative log messages and job summary notes instead
of the previous wall-of-text license warning.
- **New integration tests**: Adds `integ-test-basic-cache-provider.yml`
workflow that seeds and verifies the basic cache provider across
platforms, plus unit tests for `BasicCacheService` and `getCacheService`
selection logic.
- **CI workflow reorganization**: Dependency-submission integration
tests extracted into their own reusable suite
(`suite-integ-test-dependency-submission.yml`); sample project tests
moved into the caching suite.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/ci-integ-test-full.yml

@@ -24,6 +24,16 @@ jobs:
       skip-dist: true
     secrets: inherit
 
+  dependency-submission-integ-tests:
+    uses: ./.github/workflows/suite-integ-test-dependency-submission.yml
+    concurrency:
+      group: CI-integ-test-full
+      cancel-in-progress: false
+    with:
+      runner-os: '["ubuntu-latest", "windows-latest", "macos-latest"]'
+      skip-dist: true
+    secrets: inherit
+
   other-integ-tests:
     permissions:
       contents: write

.github/workflows/ci-integ-test.yml

@@ -28,7 +28,7 @@ jobs:
     needs: build-distribution
     uses: ./.github/workflows/suite-integ-test-caching.yml
     concurrency:
-      group: CI-integ-test
+      group: CI-integ-test-caching
       cancel-in-progress: false
     with:
       skip-dist: false
@@ -37,10 +37,22 @@ jobs:
   other-integ-tests:
     permissions:
       contents: write
-    needs: build-distribution
+    needs: caching-integ-tests
     uses: ./.github/workflows/suite-integ-test-other.yml
     concurrency:
-      group: CI-integ-test
+      group: CI-integ-test-other
+      cancel-in-progress: false
+    with:
+      skip-dist: false
+    secrets: inherit
+
+  dependency-submission-integ-tests:
+    permissions:
+      contents: write
+    needs: other-integ-tests
+    uses: ./.github/workflows/suite-integ-test-dependency-submission.yml
+    concurrency:
+      group: CI-integ-test-dependency-submission
       cancel-in-progress: false
     with:
       skip-dist: false

.github/workflows/demo-job-summary.yml

@@ -132,6 +132,23 @@ jobs:
       working-directory: .github/workflow-samples/kotlin-dsl
       run: ./gradlew assemble
 
+  basic-caching:
+    needs: build-distribution
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout sources
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+    - name: Initialize integ-test
+      uses: ./.github/actions/init-integ-test
+
+    - name: Setup Gradle
+      uses: ./setup-gradle
+      with:
+        cache-provider: basic
+    - name: Build kotlin-dsl project
+      working-directory: .github/workflow-samples/kotlin-dsl
+      run: ./gradlew assemble
+
   terms-of-use-accepted:
     needs: build-distribution
     runs-on: ubuntu-latest

.github/workflows/integ-test-basic-cache-provider.yml

@@ -0,0 +1,67 @@
+name: Test basic cache provider
+
+on:
+  workflow_call:
+    inputs:
+      cache-key-prefix:
+        type: string
+        default: '0'
+      runner-os:
+        type: string
+        default: '["ubuntu-latest"]'
+      skip-dist:
+        type: boolean
+        default: false
+
+env:
+  SKIP_DIST: ${{ inputs.skip-dist }}
+  GRADLE_BUILD_ACTION_CACHE_KEY_PREFIX: basic-cache-provider-${{ inputs.cache-key-prefix }}
+
+permissions:
+  contents: read
+
+jobs:
+  basic-cache-seed-build:
+    strategy:
+      max-parallel: 1
+      fail-fast: false
+      matrix:
+        os: ${{fromJSON(inputs.runner-os)}}
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Checkout sources
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+    - name: Initialize integ-test
+      uses: ./.github/actions/init-integ-test
+
+    - name: Setup Gradle with basic cache provider
+      uses: ./setup-gradle
+      with:
+        cache-provider: basic
+        cache-read-only: false # For testing, allow writing cache entries on non-default branches
+    - name: Build kotlin-dsl project
+      working-directory: .github/workflow-samples/kotlin-dsl
+      run: ./gradlew build
+
+  basic-cache-verify-build:
+    needs: basic-cache-seed-build
+    strategy:
+      max-parallel: 1
+      fail-fast: false
+      matrix:
+        os: ${{fromJSON(inputs.runner-os)}}
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Checkout sources
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+    - name: Initialize integ-test
+      uses: ./.github/actions/init-integ-test
+
+    - name: Setup Gradle with basic cache provider
+      uses: ./setup-gradle
+      with:
+        cache-provider: basic
+        cache-read-only: true
+    - name: Build kotlin-dsl project
+      working-directory: .github/workflow-samples/kotlin-dsl
+      run: ./gradlew build --offline

.github/workflows/suite-integ-test-caching.yml

@@ -45,3 +45,21 @@ jobs:
     uses: ./.github/workflows/integ-test-restore-java-toolchain.yml
     with:
       skip-dist: ${{ inputs.skip-dist }}
+
+  sample-kotlin-dsl:
+    uses: ./.github/workflows/integ-test-sample-kotlin-dsl.yml
+    with:
+      runner-os: '${{ inputs.runner-os }}'
+      skip-dist: ${{ inputs.skip-dist }}
+
+  sample-gradle-plugin:
+    uses: ./.github/workflows/integ-test-sample-gradle-plugin.yml
+    with:
+      runner-os: '${{ inputs.runner-os }}'
+      skip-dist: ${{ inputs.skip-dist }}
+
+  basic-cache-provider:
+    uses: ./.github/workflows/integ-test-basic-cache-provider.yml
+    with:
+      runner-os: '${{ inputs.runner-os }}'
+      skip-dist: ${{ inputs.skip-dist }}

.github/workflows/suite-integ-test-dependency-submission.yml

@@ -0,0 +1,43 @@
+name: suite-integ-test-dependency-submission
+
+on:
+  workflow_call:
+    inputs:
+      runner-os:
+        type: string
+        default: '["ubuntu-latest"]'
+      skip-dist:
+        type: boolean
+        default: false
+
+permissions:
+  contents: read
+
+jobs:
+  dependency-graph:
+    if: ${{ ! github.event.pull_request.head.repo.fork }}
+    uses: ./.github/workflows/integ-test-dependency-graph.yml
+    permissions:
+      contents: write
+    with:
+      runner-os: '${{ inputs.runner-os }}'
+      skip-dist: ${{ inputs.skip-dist }}
+
+  dependency-submission:
+    if: ${{ ! github.event.pull_request.head.repo.fork }}
+    uses: ./.github/workflows/integ-test-dependency-submission.yml
+    permissions:
+      contents: write
+    with:
+      runner-os: '${{ inputs.runner-os }}'
+      skip-dist: ${{ inputs.skip-dist }}
+
+  dependency-submission-failures:
+    if: ${{ ! github.event.pull_request.head.repo.fork }}
+    uses: ./.github/workflows/integ-test-dependency-submission-failures.yml
+    permissions:
+      contents: write
+    with:
+      runner-os: '${{ inputs.runner-os }}'
+      skip-dist: ${{ inputs.skip-dist }}
+

.github/workflows/suite-integ-test-other.yml

@@ -20,33 +20,6 @@ jobs:
       runner-os: '${{ inputs.runner-os }}'
       skip-dist: ${{ inputs.skip-dist }}
 
-  dependency-graph:
-    if: ${{ ! github.event.pull_request.head.repo.fork }}
-    uses: ./.github/workflows/integ-test-dependency-graph.yml
-    permissions:
-      contents: write
-    with:
-      runner-os: '${{ inputs.runner-os }}'
-      skip-dist: ${{ inputs.skip-dist }}
-
-  dependency-submission:
-    if: ${{ ! github.event.pull_request.head.repo.fork }}
-    uses: ./.github/workflows/integ-test-dependency-submission.yml
-    permissions:
-      contents: write
-    with:
-      runner-os: '${{ inputs.runner-os }}'
-      skip-dist: ${{ inputs.skip-dist }}
-
-  dependency-submission-failures:
-    if: ${{ ! github.event.pull_request.head.repo.fork }}
-    uses: ./.github/workflows/integ-test-dependency-submission-failures.yml
-    permissions:
-      contents: write
-    with:
-      runner-os: '${{ inputs.runner-os }}'
-      skip-dist: ${{ inputs.skip-dist }}
-
   develocity-injection:
     if: ${{ ! github.event.pull_request.head.repo.fork }}
     uses: ./.github/workflows/integ-test-inject-develocity.yml
@@ -61,18 +34,6 @@ jobs:
       runner-os: '${{ inputs.runner-os }}'
       skip-dist: ${{ inputs.skip-dist }}
 
-  sample-kotlin-dsl:
-    uses: ./.github/workflows/integ-test-sample-kotlin-dsl.yml
-    with:
-      runner-os: '${{ inputs.runner-os }}'
-      skip-dist: ${{ inputs.skip-dist }}
-
-  sample-gradle-plugin:
-    uses: ./.github/workflows/integ-test-sample-gradle-plugin.yml
-    with:
-      runner-os: '${{ inputs.runner-os }}'
-      skip-dist: ${{ inputs.skip-dist }}
-
   toolchain-detection:
     uses: ./.github/workflows/integ-test-detect-toolchains.yml
     with: