Checkstyle Java generics: '?' is not preceded with whitespace

Question

I am using plugin

<artifactId>maven-checkstyle-plugin</artifactId>
<version>2.17</version>

It has 6.11.2 checkstyle version. Configuration saying about whitespaces is:

<module name="NoWhitespaceAfter">
    <property name="severity" value="error" />
    <property name="tokens" value="ARRAY_INIT,BNOT,DEC,DOT,INC,LNOT" />
</module>
<module name="NoWhitespaceBefore">
    <property name="severity" value="error" />
</module>
<module name="RedundantModifier">
    <property name="severity" value="error" />
</module>
<module name="WhitespaceAround">
    <property name="severity" value="error" />
    <property name="tokens" value="ASSIGN,BAND,BAND_ASSIGN,BOR,BOR_ASSIGN,BSR,BSR_ASSIGN,BXOR,BXOR_ASSIGN,COLON,DIV,DIV_ASSIGN,DO_WHILE,EQUAL,GE,LAND,LCURLY,LE,LITERAL_ASSERT,LITERAL_CATCH,LITERAL_DO,LITERAL_ELSE,LITERAL_FINALLY,LITERAL_FOR,LITERAL_IF,LITERAL_RETURN,LITERAL_SYNCHRONIZED,LITERAL_TRY,LITERAL_WHILE,LOR,MINUS,MINUS_ASSIGN,MOD,MOD_ASSIGN,NOT_EQUAL,PLUS,PLUS_ASSIGN,RCURLY,SL,SLIST,SL_ASSIGN,SR,SR_ASSIGN,STAR,STAR_ASSIGN,TYPE_EXTENSION_AND" />
</module>

I always get this error:

(whitespace) WhitespaceAround: WhitespaceAround: '?' is not preceded with whitespace.  
(whitespace) WhitespaceAround: WhitespaceAround: '?' is not followed by whitespace.
Empty blocks may only be represented as {} when not part of a multi-block statement (4.1.3)

The code snippets are:

Class<?>[] groups() default {};  
Class<? extends Payload>[] payload() default {};

I tried to remove the snippet with whitespaces, but still get the same error.

Answer 1

It is a bug in checkstyle, it has been fixed in Checkstyle 6.14 (see https://github.com/checkstyle/checkstyle/issues/2633)

You can upgrade checkstyle by adding a <dependencies> section in the maven-checkstyle-plugin:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-checkstyle-plugin</artifactId>
    <version>2.17</version>
    <dependencies>
        <dependency>
            <groupId>com.puppycrawl.tools</groupId>
            <artifactId>checkstyle</artifactId>
            <version>6.14</version>
        </dependency>
    </dependencies>
</plugin>

Or you can go straight to the newest Checkstyle (7.0).