[MWRAPPER-33] Adopt Java 8 constructs

[timtebeek]

Java 8 brought some possible code improvements over the previous Java 7. These have been applied through:

mvn org.openrewrite.maven:rewrite-maven-plugin:4.38.2:run -DactiveRecipes=org.openrewrite.java.cleanup.CommonStaticAnalysis

With the following results

Changes have been made to
maven-wrapper/src/main/java/org/apache/maven/wrapper/cli/CommandLineParser.java by:
    org.openrewrite.java.cleanup.CommonStaticAnalysis
        org.openrewrite.java.cleanup.EqualsAvoidsNull
        org.openrewrite.java.cleanup.FinalClass
        org.openrewrite.java.cleanup.UseDiamondOperator
Changes have been made to
maven-wrapper/src/main/java/org/apache/maven/wrapper/cli/ParsedCommandLineOption.java by:
    org.openrewrite.java.cleanup.CommonStaticAnalysis
        org.openrewrite.java.cleanup.UseDiamondOperator
Changes have been made to
maven-wrapper/src/main/java/org/apache/maven/wrapper/cli/CommandLineOption.java by:
    org.openrewrite.java.cleanup.CommonStaticAnalysis
        org.openrewrite.java.cleanup.UseDiamondOperator
Changes have been made to
maven-wrapper/src/main/java/org/apache/maven/wrapper/cli/ParsedCommandLine.java by:
    org.openrewrite.java.cleanup.CommonStaticAnalysis
        org.openrewrite.java.cleanup.UseDiamondOperator
Changes have been made to
maven-wrapper/src/main/java/org/apache/maven/wrapper/cli/AbstractPropertiesCommandLineConverter.java by:
    org.openrewrite.java.cleanup.CommonStaticAnalysis
        org.openrewrite.java.cleanup.UseDiamondOperator
Changes have been made to
maven-wrapper/src/test/java/org/apache/maven/wrapper/SystemPropertiesHandlerTest.java by:
    org.openrewrite.java.cleanup.CommonStaticAnalysis
        org.openrewrite.java.cleanup.UseDiamondOperator
Changes have been made to
maven-wrapper-plugin/src/main/java/org/apache/maven/plugins/wrapper/WrapperMojo.java by:
    org.openrewrite.java.cleanup.CommonStaticAnalysis
        org.openrewrite.java.cleanup.UseLambdaForFunctionalInterface

A few private classes have been made final, but I don't suppose that will be an issue.

All of these changes were automated, so I don't feel particularly attached to them/
Feel free to provide honest feedback if these types of changes are not welcome! :)

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[timtebeek]

And a small note perhaps that the recent shellcheck step also runs (and fails) on forks, so some changes there might be in order.

[bmarwell]

Yes, checks will work again after #79 is merged (reviews, please!).

[timtebeek]

@bmarwell As discussed I've force pushed to this branch now that the parent and formatting has changed in master. Ready for review & merge.

[bmarwell]

LGTM!