chore: Run Java 7 Tests

[lqiu96]

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Fixes #<issue_number_goes_here> ☕️

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[generated-files-bot]

Warning: This pull request is touching the following templated files:

• .github/workflows/ci.yaml
• .kokoro/build.sh
• .kokoro/common.sh

[lqiu96]

Apache Maven 3.8.6 (84538c9988a25aec085021c365c560670ad80f63)
Maven home: /usr/share/apache-maven-3.8.6
Java version: 1.7.0_352, vendor: Azul Systems, Inc., runtime: /opt/hostedtoolcache/Java_Zulu_jdk/7.0.352-1/x64/jre
Default locale: en, platform encoding: UTF-8
OS name: "linux", version: "5.15.0-1019-azure", arch: "amd64", family: "unix"

Apache Maven 3.8.6 (84538c9988a25aec085021c365c560670ad80f63)

Confirmed this the correct hash for Maven 3.8.6 and not an Ubuntu wrapper.

[lqiu96]

Runing mvn gives this error message:

Error: Exception in thread "main" java.lang.UnsupportedClassVersionError: com/fasterxml/jackson/databind/ObjectMapper : Unsupported major.minor version 52.0
	at java.lang.ClassLoader.defineClass1(Native Method)

Version 52 -> Java 8. The official docs say maven 3.8.6 is compatible with Java 7+. Not sure where it is pulling in Java 8 requirement from.

[lqiu96]

Testing locally now:

Using Java 7 Zulu via SDKMan:
| >>> | 7.0.352 | zulu | installed | 7.0.352-zulu

Seeing this error when running Java 7:

Exception in thread "main" java.lang.UnsupportedClassVersionError: com/google/inject/Module : Unsupported major.minor version 52.0

Seems unrelated to the Matrix environment in Github Actions
Fix: This is due to not using Apache Maven (check the checksum). When you install the official one locally, you get

Exception in thread "main" java.lang.UnsupportedClassVersionError: com/fasterxml/jackson/databind/ObjectMapper : Unsupported major.minor version 52.0

Maven version + Java version is correct

lawrenceqiu@lawrenceqiu:~/IdeaProjects/google-http-java-client$ mvn -v
Apache Maven 3.8.6 (84538c9988a25aec085021c365c560670ad80f63)
Maven home: /opt/apache-maven-3.8.6
Java version: 1.7.0_352, vendor: Azul Systems, Inc., runtime: /usr/local/google/home/lawrenceqiu/.sdkman/candidates/java/7.0.352-zulu/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "5.17.11-1rodete2-amd64", arch: "amd64", family: "unix"

Java Compiler is correct

lawrenceqiu@lawrenceqiu:~/IdeaProjects/google-http-java-client$ javac -version
javac 1.7.0_352

$JAVA_HOME

lawrenceqiu@lawrenceqiu:~/IdeaProjects/google-http-java-client$ echo $JAVA_HOME
/usr/local/google/home/lawrenceqiu/.sdkman/candidates/java/7.0.352-zulu

[lqiu96]

Plan: Rollback the maven versions to see when it becomes compatible with Java 7.

[lqiu96]

Testing locally:

lawrenceqiu@lawrenceqiu:~$ java -version
openjdk version "1.7.0_352"
OpenJDK Runtime Environment (Zulu 7.56.0.11-CA-linux64) (build 1.7.0_352-b01)
OpenJDK 64-Bit Server VM (Zulu 7.56.0.11-CA-linux64) (build 24.352-b01, mixed mode)
lawrenceqiu@lawrenceqiu:~$ mvn -v
Apache Maven 3.5.4 (1edded0938998edf8bf061f1ceb3cfdeccf443fe; 2018-06-17T18:33:14Z)
Maven home: /opt/apache-maven-3.5.4
Java version: 1.7.0_352, vendor: Azul Systems, Inc., runtime: /usr/local/google/home/lawrenceqiu/.sdkman/candidates/java/7.0.352-zulu/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "5.18.16-1rodete1-amd64", arch: "amd64", family: "unix"
lawrenceqiu@lawrenceqiu:~$ mvn
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.116 s
[INFO] Finished at: 2022-09-22T19:53:49Z
[INFO] ------------------------------------------------------------------------
...

Seems like the last version compatible with Java 7 is Maven version 3.5.4 It does not look compatible

[lqiu96]

Using https://github.com/stCarolas/setup-maven Github Action to set mvn -v to 3.5.4