Upgrade to Checkstyle 8.21

[snicoll]

This project uses the latest checkstyle release at that time (8.21). Trying to use 0.0.12 with that version on the initializr repository leads to:

Caused by: org.apache.maven.plugin.PluginExecutionException: Execution checkstyle-validation of goal org.apache.maven.plugins:maven-checkstyle-plugin:3.1.0:check failed: An API incompatibility was encountered while executing org.apache.maven.plugins:maven-checkstyle-plugin:3.1.0:check: java.lang.VerifyError: class io.spring.javaformat.checkstyle.SpringChecks overrides final method setTabWidth.(I)V
-----------------------------------------------------
realm =    plugin>org.apache.maven.plugins:maven-checkstyle-plugin:3.1.0

This can be reproduced by upgrading the checkstyle version locally

[wilkinsona]

It was added in 8.19.

[snicoll]

Would it be possible to add an integration test in this project or something? The project currently build with that version and I'd expect it to fail.

[rajadilipkolli]

Any temporary solution ?

[wilkinsona]

You'll have to use Checkstyle 8.18 or earlier for now.

[wilkinsona]

8.21 has changed how try-with-resources is treated and the formatter and Checkstyle now disagree. The formatter produces this:

try (InputStream foo = getInputStreamFor("foo"); InputStream bar = getInputStreamFor("bar")) {
   // …
}

Checkstyle reports an error due to multiple statements:

[ERROR] src/test/java/org/springframework/boot/configurationmetadata/ConfigurationMetadataRepositoryJsonBuilderTests.java:[66,64] (coding) OneStatementPerLine: Only one statement per line allowed.
[ERROR] src/test/java/org/springframework/boot/configurationmetadata/ConfigurationMetadataRepositoryJsonBuilderTests.java:[79,64] (coding) OneStatementPerLine: Only one statement per line allowed.
[ERROR] src/test/java/org/springframework/boot/configurationmetadata/ConfigurationMetadataRepositoryJsonBuilderTests.java:[92,64] (coding) OneStatementPerLine: Only one statement per line allowed.
[ERROR] src/test/java/org/springframework/boot/configurationmetadata/ConfigurationMetadataRepositoryJsonBuilderTests.java:[138,64] (coding) OneStatementPerLine: Only one statement per line allowed.

A change in Checkstyle is being discussed and a PR has been proposed. AIUI, the proposed change will mean that an error is no longer reported by default with a property to turn it on.

I'm not sure if we should:

1. wait for a new Checkstyle release
2. change the formatter to split the code onto multiple lines
3. do something else

[philwebb]

Changing the formatter is never easy so I'm tempted to fix it at checkstyle. Perhaps we can create our own local copy of that rule until the 8.22 is released.