Exclude external and generated files from spell checking

Spell checking is currently being applied to external / generated files, which causes significant and unnecessary maintenance effort and cost, without providing any real value.

This became visible after the changes introduced in:

• Issue #17487: Add UpdateMavenWrapper #18434

As a result, files that are not authored or maintained by the Checkstyle project (for example:
generated files, vendored files, or third-party content) are now subject to spelling validation.

Why this is a problem

• External files are not under project control
• Fixing spelling issues in such files is either:
  • impossible, or
  • creates constant rework when those files are regenerated or updated
• This leads to:
  • noisy CI failures
  • wasted developer time
  • increased contribution friction
  • no actual improvement in Checkstyle source quality

In short: high cost, zero benefit.

Expected behavior

Spell checking should be limited to files that are owned and maintained by the project, for example:

• source code
• documentation authored by the project

External, generated, or third-party files should be explicitly excluded from spell checking.

Actual behavior

Spell checking is applied broadly, including external files, which causes repeated failures and manual intervention.

Visual examples

Screenshots showing the issue in practice:

Request

Please exclude external files from spell checking, or provide a supported configuration mechanism to opt them out.

This would significantly reduce unnecessary maintenance effort while keeping spell checking effective where it actually matters.

ONLY:

• mvnw files
• config/rewrite.yml