Issue #7877: Removed redundant conditional

[bossever]

Fixes #7877

Pitest Report before fix: https://bossever.github.io/issue7877/pit-reports/202102122217/com.puppycrawl.tools.checkstyle.checks.imports/ImportOrderCheck.java.html#org.pitest.mutationtest.report.html.SourceFile@476dda8b_878

Hardcoded mutation on line 878: removed conditional - replaced equality check with true → SURVIVED

Pitest Report after fix: https://bossever.github.io/issue7877/pit-reports/202102182308/com.puppycrawl.tools.checkstyle.checks.imports/index.html

Rationale behind removing !beforeFirstImport

I tried coming up with test cases where the mutation could be killed, but came to the conclusion that there exists no such test case, please read comment on issue - #7877 (comment).
As @nmancus1 has pointed out in issue conversation, I suppose this condition can be safely removed if no test cases were found, and mvn clean verify is passing.
Please let me know if I have missed anything, or if there is another way to fix this issue.

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Diff Regression config: https://gist.githubusercontent.com/bossever/ff126a13b0f1422daa5626db6fcdc384/raw/96d1898cdc28233c7a7fef6b3f855b939b2cf694/config.xml

Diff Regression projects: https://gist.githubusercontent.com/bossever/ff126a13b0f1422daa5626db6fcdc384/raw/6e8f8cbf0eb40baaf072ec9a3fe93883614709a9/projects-to-test-on.properties

Report label: Diff Regression Report after fix

[bossever]

GitHub, generate report

[github-actions]

Diff Regression Report after fix: https://checkstyle-diff-reports.s3.us-east-2.amazonaws.com/pitestIssue6_2021193057/reports/diff/index.html

[nrmancuso]

To make a test case for this condition, I think we would need to report a violation for an internal separation of imports before the first import (while processing the first import, really). I also don't think it makes sense to make some impossible test case(via reflection, etc.) to kill this mutation.