Suppress checkstyle for lombok's val using SuppressionXpathFilter

I am using lombok's val to specify the final variables in my code. The checkstyle rule for FinalLocalVariable reports any val variable as non-final. I am trying to write a custom suppress.xml to suppress this check for any val field. Currently, my suppression.xml looks like this

<?xml version="1.0"?>
<!DOCTYPE suppressions PUBLIC
    "-//Checkstyle//DTD SuppressionXpathFilter Experimental Configuration 1.2//EN"
    "https://checkstyle.org/dtds/suppressions_1_2_xpath_experimental.dtd">
 <suppressions>
<suppress-xpath 
        checks="FinalLocalVariable" query="//VARIABLE_DEF[./TYPE/IDENT[@text='val']]"/
</suppressions>

I have generated the AST tree for the class that has the val fields, here is the part where val is declared

`--SLIST -> { [32:96]
    |       |--VARIABLE_DEF -> VARIABLE_DEF [33:4]
    |       |   |--MODIFIERS -> MODIFIERS [33:4]
    |       |   |--TYPE -> TYPE [33:4]
    |       |   |   `--IDENT -> val [33:4]

My idea was to specify that any variable definition of identity val should be ignored for this exact check. I have read the checkstyle's documentation for SuppressionXpathFilter and I cannot find what my issue is as the checkstyle keeps reporting that the variable should be declared final. Any help would be much appreciated.

Solution

You need to address the IDENT child node of the VARIABLE_DEF with the suppression query:

query="//VARIABLE_DEF[./TYPE/IDENT[@text='val']]/IDENT"

For the following source code:

class C {
    void m() {
        val a = 3;
    }
}

with the following checkstyle config:

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
        "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
<module name="Checker">
    <property name="fileExtensions" value="java"/>
    <module name="TreeWalker">
        <module name="SuppressionXpathFilter">
            <property name="file" value="suppressions-check.xml"/>
        </module>
        <module name="FinalLocalVariable"/>
    </module>
</module>

using this suppression filter file:

<?xml version="1.0"?>
<!DOCTYPE suppressions PUBLIC
        "-//Checkstyle//DTD SuppressionXpathFilter Experimental Configuration 1.2//EN"
        "https://checkstyle.org/dtds/suppressions_1_2_xpath_experimental.dtd">
<suppressions>
    <suppress-xpath checks="FinalLocalVariable" query="//VARIABLE_DEF[./TYPE/IDENT[@text='val']]/IDENT"/>
</suppressions>

Checkstyle won't report any error.