After upgrade 5.41 -> 5.42 formatter adds additional \n between static and normal imports

[DorianOlympia]

After upgrade 5.41 -> 5.42 formatter adds two \n between static and normal imports (according to xml checkstyle i should be once):

import static X;
import Y;"

is refactored to:

import static X;


import Y;

even though according to checkstyle xml it should be:

import static X;

import Y;

This leads to inconsistency between checkstyle and formatter rules.

[jshiell]

Curious. There have been no changes in the formatter for some releases, so no idea what has triggered this.

Now the bad bit: the formatter was a contribution, so I don't know the code well, nor TBH do I have much interest in it. So the chances of this getting fixed by me aren't high. Sorry.

[dominicboeck]

I took a look at the source code since this is a rather annoying issue. I hope I can offer a bit more context and a workaround with this comment.

I am using the following rule in my checkstyle configuration (by default this is actually part of the google_checks.xml):

<module name="CustomImportOrder">
    <property name="sortImportsInGroupAlphabetically" value="true"/>
    <property name="separateLineBetweenGroups" value="true"/>
    <property name="customImportOrderRules" value="STATIC###THIRD_PARTY_PACKAGE"/>
    <property name="tokens" value="IMPORT, STATIC_IMPORT, PACKAGE_DEF"/>
</module>

Upon importing this checkstyle configuration in IntelliJ the formatter creates the following Import Layout table (IntelliJ settings > Editor > Code Style > Java > Imports > Import Layout):

Static	Package	With Subpackages
	import static all other imports
	<blank line>
	import .*
	<blank line>
	import all other imports

However, after closing and reopening the IntelliJ settings the Import Layout table changes as follows:

Static	Package	With Subpackages
	import static all other imports
	<blank line>
	<blank line>
	import all other imports

This is exactly the behavior mentioned by @DorianOlympia. I did not look into the actual reason why this is happening, but as a workaround it is possible to remove THIRD_PARTY_PACKAGE from the customImportOrderRules property:

<module name="CustomImportOrder">
    <property name="sortImportsInGroupAlphabetically" value="true"/>
    <property name="separateLineBetweenGroups" value="true"/>
    <property name="customImportOrderRules" value="STATIC"/>
    <property name="tokens" value="IMPORT, STATIC_IMPORT, PACKAGE_DEF"/>
</module>

Looking into the checkstyle documentation for CustomImportOrder this actually makes sense, due to the default value of THIRD_PARTY_PACKAGE. Combined with the program flow starting from line 93 in CustomImportOrderImporter.java this causes the creation of import .* followed by <blank line>. Removing THIRD_PARTY_PACKAGE therefore leads to the expected Import Layout:

Static	Package	With Subpackages
	import static all other imports
	<blank line>
	import all other imports

[jshiell]

Thanks @dominicboeck - lovely work!

I've made a change so that THIRD_PARTY_PACKAGE/SPECIAL_IMPORTS will be ignored if thirdPartyPackageRegExp/specialImportsRegExp are undefined, which I believe should avoid this nastiness.