feat!: drops support of Java 7 (#946)

* feat!: drops support of Java 7

From the next major release we will be only supporting Java 8+

* tests: do not run unit tests for java 7

.github/sync-repo-settings.yaml

@@ -34,7 +34,6 @@ branchProtectionRules:
     - "linkage-monitor"
     - "lint"
     - "clirr"
-    - "units (7)"
     - "units (8)"
     - "units (11)"
     - "Kokoro - Test: Integration"

.github/workflows/ci.yaml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [7, 8, 11]
+        java: [8, 11]
     steps:
     - uses: actions/checkout@v2
     - uses: actions/setup-java@v1
@@ -80,4 +80,4 @@ jobs:
     - run: java -version
     - run: .kokoro/build.sh
       env:
-        JOB_TYPE: clirr
+        JOB_TYPE: clirr

CONTRIBUTING.md

@@ -57,12 +57,9 @@ Code Samples must be bundled in separate Maven modules, and guarded by a
 Maven profile with the name `enable-samples`.
 
 The samples must be separate from the primary project for a few reasons:
-1. Primary projects have a minimum Java version of Java 7 whereas samples have
-   a minimum Java version of Java 8. Due to this we need the ability to
-   selectively exclude samples from a build run.
-2. Many code samples depend on external GCP services and need
+1. Many code samples depend on external GCP services and need
    credentials to access the service.
-3. Code samples are not released as Maven artifacts and must be excluded from 
+2. Code samples are not released as Maven artifacts and must be excluded from
    release builds.
 
 ### Building

README.md

@@ -258,7 +258,7 @@ Cloud Spanner uses gRPC for the transport layer.
 
 ## Java Versions
 
-Java 7 or above is required for using this client.
+Java 8 or above is required for using this client.
 
 ## Versioning
 
@@ -285,7 +285,6 @@ Apache 2.0 - See [LICENSE][license] for more information.
 
 Java Version | Status
 ------------ | ------
-Java 7 | [![Kokoro CI][kokoro-badge-image-1]][kokoro-badge-link-1]
 Java 8 | [![Kokoro CI][kokoro-badge-image-2]][kokoro-badge-link-2]
 Java 8 OSX | [![Kokoro CI][kokoro-badge-image-3]][kokoro-badge-link-3]
 Java 8 Windows | [![Kokoro CI][kokoro-badge-image-4]][kokoro-badge-link-4]
@@ -295,8 +294,6 @@ Java is a registered trademark of Oracle and/or its affiliates.
 
 [product-docs]: https://cloud.google.com/spanner/docs/
 [javadocs]: https://googleapis.dev/java/google-cloud-spanner/latest/
-[kokoro-badge-image-1]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-spanner/java7.svg
-[kokoro-badge-link-1]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-spanner/java7.html
 [kokoro-badge-image-2]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-spanner/java8.svg
 [kokoro-badge-link-2]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-spanner/java8.html
 [kokoro-badge-image-3]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-spanner/java8-osx.svg