➜  src cat Test.java                                         
public class Test {

    /**
     *
     * @param ᇤᇥᇦᇧᇨᇩᇪᇫᇬᇭᇮ
     */
    void aᇭᇮᇯᇰᇱᇲᇳᇴᇵᇶᇷᇸᇹᇺ(int ᇤᇥᇦᇧᇨᇩᇪᇫᇬᇭᇮ) {}


}

 ➜  src java -jar checkstyle-9.0-SNAPSHOT-all.jar -T Test.java
CLASS_DEF -> CLASS_DEF [1:0]
|--MODIFIERS -> MODIFIERS [1:0]
|   `--LITERAL_PUBLIC -> public [1:0]
|--LITERAL_CLASS -> class [1:7]
|--IDENT -> Test [1:13]
`--OBJBLOCK -> OBJBLOCK [1:18]
    |--LCURLY -> { [1:18]
    |--METHOD_DEF -> METHOD_DEF [7:4]
    |   |--MODIFIERS -> MODIFIERS [7:4]
    |   |--TYPE -> TYPE [7:4]
    |   |   |--BLOCK_COMMENT_BEGIN -> /* [3:4]
    |   |   |   |--COMMENT_CONTENT -> *\n     *\n     * @param ᇤᇥᇦᇧᇨᇩᇪᇫᇬᇭᇮ\n      [3:6]
    |   |   |   `--BLOCK_COMMENT_END -> */ [6:5]
    |   |   `--LITERAL_VOID -> void [7:4]
    |   |--IDENT -> aᇭᇮᇯᇰᇱᇲᇳᇴᇵᇶᇷᇸᇹᇺ [7:9]
    |   |--LPAREN -> ( [7:24]
    |   |--PARAMETERS -> PARAMETERS [7:25]
    |   |   `--PARAMETER_DEF -> PARAMETER_DEF [7:25]
    |   |       |--MODIFIERS -> MODIFIERS [7:25]
    |   |       |--TYPE -> TYPE [7:25]
    |   |       |   `--LITERAL_INT -> int [7:25]
    |   |       `--IDENT -> ᇤᇥᇦᇧᇨᇩᇪᇫᇬᇭᇮ [7:29]
    |   |--RPAREN -> ) [7:40]
    |   `--SLIST -> { [7:42]
    |       `--RCURLY -> } [7:43]
    `--RCURLY -> } [10:0]

 ➜  src java -jar checkstyle-9.0-SNAPSHOT-all.jar -J Test.java
Exception in thread "main" java.lang.IllegalArgumentException: [ERROR:5] Javadoc comment at column 15 has parse error. Details: no viable alternative at input 'ᇤ' while parsing JAVADOC_TAG
        at com.puppycrawl.tools.checkstyle.DetailNodeTreeStringPrinter.parseJavadocAsDetailNode(DetailNodeTreeStringPrinter.java:71)
        at com.puppycrawl.tools.checkstyle.AstTreeStringPrinter.parseAndPrintJavadocTree(AstTreeStringPrinter.java:116)
        at com.puppycrawl.tools.checkstyle.AstTreeStringPrinter.printJavaAndJavadocTree(AstTreeStringPrinter.java:97)
        at com.puppycrawl.tools.checkstyle.AstTreeStringPrinter.printJavaAndJavadocTree(AstTreeStringPrinter.java:101)
        at com.puppycrawl.tools.checkstyle.AstTreeStringPrinter.printJavaAndJavadocTree(AstTreeStringPrinter.java:101)
        at com.puppycrawl.tools.checkstyle.AstTreeStringPrinter.printJavaAndJavadocTree(AstTreeStringPrinter.java:101)
        at com.puppycrawl.tools.checkstyle.AstTreeStringPrinter.printJavaAndJavadocTree(AstTreeStringPrinter.java:101)
        at com.puppycrawl.tools.checkstyle.AstTreeStringPrinter.printJavaAndJavadocTree(AstTreeStringPrinter.java:101)
        at com.puppycrawl.tools.checkstyle.AstTreeStringPrinter.printJavaAndJavadocTree(AstTreeStringPrinter.java:79)
        at com.puppycrawl.tools.checkstyle.Main.runCli(Main.java:306)
        at com.puppycrawl.tools.checkstyle.Main.execute(Main.java:191)
        at com.puppycrawl.tools.checkstyle.Main.main(Main.java:126)

 checkstyle git:(master) cat $(find . -name "JavadocLexer.g4") | grep "\["
CUSTOM_NAME: '@' [a-zA-Z0-9:._-]+ {isJavadocTagAvailable}?;
PARAMETER_NAME: [a-zA-Z0-9<>_$]+ -> mode(DEFAULT_MODE);
CLASS: [A-Z] [a-zA-Z0-9_$]* {referenceCatched = true;};
MEMBER: [a-zA-Z0-9_$]+ {!insideReferenceArguments}?;
ARGUMENT: ([a-zA-Z0-9_$] | '.' | '[' | ']')+ {insideReferenceArguments}?;
FIELD_NAME: [a-zA-Z0-9_$]+ -> mode(serialFieldFieldType);
FIELD_TYPE: [a-zA-Z0-9_$]+ -> mode(DEFAULT_MODE);
CLASS_NAME: ([a-zA-Z0-9_$] | '.')+ -> mode(DEFAULT_MODE);
CustomName1: '@' [a-zA-Z0-9:._-]+ {recognizeXmlTags=false;}
Brackets: '{' (~[}] | Brackets)* '}' -> type(CHAR);
Text: ~[}] -> type(CHAR);
fragment JavaLetter: [A-Za-z_$];
fragment JavaLetterOrDigit: [0-9A-Za-z_$];
HEXDIGIT    :   [a-fA-F0-9] ;
DIGIT       :   [0-9] ;
            :   [:a-zA-Z]
FragmentReference: ([a-zA-Z0-9_-] | '.')+
      | ([a-zA-Z0-9_-] | '.')* '#' [a-zA-Z0-9_-]+ ( '(' (([a-zA-Z0-9_-] | '.')+ | ',' | ' ')* ')' )?
ATTR_VALUE  : '"' ~[<"]* '"'        {!attributeCatched}? {attributeCatched=true;}
            | '\'' ~[<']* '\''      {!attributeCatched}? {attributeCatched=true;}
            | (~[> \t\r\n/] | SlashInAttr)+ {!attributeCatched}? {attributeCatched=true;}
CUSTOM_NAME: '@' [a-zA-Z0-9:._-]+ {isJavadocTagAvailable}?;
CLASS: [A-Z] [a-zA-Z0-9_$]* {referenceCatched = true;};
MEMBER: [a-zA-Z0-9_$]+ {!insideReferenceArguments}?;
ARGUMENT: ([a-zA-Z0-9_$] | '.' | '[' | ']')+ {insideReferenceArguments}?;
FIELD_NAME: [a-zA-Z0-9_$]+ -> mode(serialFieldFieldType);
FIELD_TYPE: [a-zA-Z0-9_$]+ -> mode(DEFAULT_MODE);
CLASS_NAME: ([a-zA-Z0-9_$] | '.')+ -> mode(DEFAULT_MODE);
CustomName1: '@' [a-zA-Z0-9:._-]+ {recognizeXmlTags=false;}
Brackets: '{' (~[}] | Brackets)* '}' -> type(CHAR);
Text: ~[}] -> type(CHAR);
    : [a-zA-Z$_]
    | ~[\u0000-\u007F\uD800-\uDBFF]
    | [\uD800-\uDBFF] [\uDC00-\uDFFF]
    | [0-9]
HEXDIGIT    :   [a-fA-F0-9] ;
DIGIT       :   [0-9] ;
            :   [:a-zA-Z]
FragmentReference: ([a-zA-Z0-9_-] | '.')+
      | ([a-zA-Z0-9_-] | '.')* '#' [a-zA-Z0-9_-]+ ( '(' (([a-zA-Z0-9_-] | '.')+ | ',' | ' ')* ')' )?
ATTR_VALUE  : '"' ~[<"]* '"'        {!attributeCatched}? {attributeCatched=true;}
            | '\'' ~[<']* '\''      {!attributeCatched}? {attributeCatched=true;}
            | (~[> \t\r\n/] | SlashInAttr)+ {!attributeCatched}? {attributeCatched=true;}