GH-204 Setting the `--release` of the Java Compiler: to stick to Java `8` avoid accidental Java `11` api use

Description

By using the source and target version configuration of maven-compiler-plugin we have no way to control the usage of Java 11 specific API. The compilation will still work but the code will fail at runtime when the jar is used with Java 8.

Until Java 8, the only way to cross compile was to use source and target versions but these configuration params do not check the compatibility of the API against the specified Java version. Starting with Java 9 we have a stricter configuration when we are cross compiling. Earlier we were using JDK 8 for compiling but since now we are using JDK 11 it is better to add this release tag to ensure Java 8 compatibility in the released jar.

Refer this link for more details: https://maven.apache.org/plugins/maven-compiler-plugin/examples/set-compiler-release.html

Example usage of Java 11 API: List<String> myList = List.of("some", "new", "java", "code");

Error for using the above line

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.12.0:compile (default-compile) on project aio-lib-java-ims: Compilation failure
[ERROR] /Users/pulgupta/Documents/codes/aio-lib-java/ims/src/main/java/com/adobe/aio/ims/util/KeyStoreUtil.java:[36,31] cannot find symbol
[ERROR]   symbol:   method of(java.lang.String,java.lang.String,java.lang.String,java.lang.String)
[ERROR]   location: interface java.util.List

Motivation and Context

Since we are now building the project with Java 11 we have to ensure that we are not using any java 11/9 released API in the code. It will ensure that we are always compatible with Java 8

How Has This Been Tested?

Verified that the compilation is failing on using java 11 features. Also verified that the generated jar is compatible with java 8 javap -cp ims/target/aio-lib-java-ims-1.1.17-SNAPSHOT.jar -verbose com.adobe.aio.ims.util.KeyStoreUtil | grep major

Screenshots (if appropriate):

Types of changes

[ ] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

[ ] I have signed the Adobe Open Source CLA.
[ ] My code follows the code style of this project.
[ ] My change requires a change to the documentation.
[ ] I have updated the documentation accordingly.
[ ] I have read the CONTRIBUTING document.
[ ] I have added tests to cover my changes.

adobe / aio-lib-java