etc/config/checkstyle.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--

    Copyright (c) 2011, 2017 Oracle and/or its affiliates. All rights reserved.

    This program and the accompanying materials are made available under the
    terms of the Eclipse Public License v. 2.0, which is available at
    http://www.eclipse.org/legal/epl-2.0.

    This Source Code may also be made available under the following Secondary
    Licenses when the conditions for such availability set forth in the
    Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
    version 2 with the GNU Classpath Exception, which is available at
    https://www.gnu.org/software/classpath/license.html.

    SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0

-->

<!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.2//EN" "http://www.puppycrawl.com/dtds/configuration_1_2.dtd">
<!--
  This file is based on maven-checkstyle-plugin config/sun_checks.xml file.

  Checkstyle configuration that checks the coding conventions based on:

    - the Java Language Specification at
      http://java.sun.com/docs/books/jls/second_edition/html/index.html

    - the Sun Code Conventions at http://java.sun.com/docs/codeconv/

    - the Javadoc guidelines at
      http://java.sun.com/j2se/javadoc/writingdoccomments/index.html

    - the JDK Api documentation http://java.sun.com/j2se/docs/api/index.html

    - some custom relaxations of the rules above & best practices

  Checkstyle is very configurable. Be sure to read the documentation at
  http://checkstyle.sf.net (or in your downloaded distribution).

  Most Checks are configurable, be sure to consult the documentation.
  To completely disable a check, just comment it out or delete it from the file.
  Finally, it is worth reading the documentation.
-->

<module name="Checker">
    <!--
        If you set the basedir property below, then all reported file
        names will be relative to the specified directory. See
        http://checkstyle.sourceforge.net/5.x/config.html#Checker

        <property name="basedir" value="${basedir}"/>
    -->

    <property name="cacheFile" value="${checkstyle.cache.file}"/>

    <!-- Checks that each Java package has a Javadoc file used for commenting. -->
    <!-- See http://checkstyle.sf.net/config_javadoc.html#JavadocPackage       -->
    <module name="JavadocPackage" />

    <!-- Checks whether files end with a new line.                        -->
    <!-- See http://checkstyle.sf.net/config_misc.html#NewlineAtEndOfFile -->
    <module name="NewlineAtEndOfFile"/>

    <!-- Checks that property files contain the same keys.         -->
    <!-- See http://checkstyle.sf.net/config_misc.html#Translation -->
    <module name="Translation"/>

    <module name="FileLength"/>

    <module name="LineLength">
        <property name="max" value="160"/>
        <property name="ignorePattern" value="@version|@see|@todo|TODO"/>
    </module>

    <!-- Following interprets the header file as regular expressions. -->
    <!-- <module name="RegexpHeader"/>                                -->

    <module name="FileTabCharacter">
        <property name="eachLine" value="true"/>
    </module>

    <module name="RegexpSingleline">
        <property name="format" value="\S+\s+$"/>
        <property name="message" value="Non-empty line has trailing spaces."/>
    </module>

    <module name="TreeWalker">
        <property name="tabWidth" value="4"/>

        <!-- Checks for Javadoc comments.                     -->
        <!-- See http://checkstyle.sf.net/config_javadoc.html -->

        <module name="JavadocMethod">
            <property name="accessModifiers" value="protected"/>
            <property name="validateThrows" value="false"/>
        </module>

        <module name="JavadocType">
            <property name="scope" value="protected"/>
        </module>
        <module name="JavadocVariable">
            <property name="scope" value="protected"/>
        </module>
        <module name="JavadocStyle"/>


        <!-- Checks for Naming Conventions.                  -->
        <!-- See http://checkstyle.sf.net/config_naming.html -->
        <module name="ConstantName"/>
        <module name="LocalFinalVariableName"/>
        <module name="LocalVariableName"/>
        <module name="MemberName"/>
        <module name="MethodName"/>
        <module name="PackageName"/>
        <module name="ParameterName"/>
        <module name="StaticVariableName"/>
        <module name="TypeName"/>


        <!-- Checks for Headers                                -->
        <!-- See http://checkstyle.sf.net/config_header.html   -->
        <!-- <module name="Header">                            -->
            <!-- The follow property value demonstrates the ability     -->
            <!-- to have access to ANT properties. In this case it uses -->
            <!-- the ${basedir} property to allow Checkstyle to be run  -->
            <!-- from any directory within a project. See property      -->
            <!-- expansion,                                             -->
            <!-- http://checkstyle.sf.net/config.html#properties        -->
            <!-- <property                                              -->
            <!--     name="headerFile"                                  -->
            <!--     value="${basedir}/java.header"/>                   -->
        <!-- </module> -->


        <!-- Checks for imports                              -->
        <!-- See http://checkstyle.sf.net/config_import.html -->
        <module name="AvoidStarImport"/>
        <module name="IllegalImport"/> <!-- defaults to sun.* packages -->
        <module name="RedundantImport"/>
        <module name="UnusedImports"/>


        <!-- Checks for Size Violations.                    -->
        <!-- See http://checkstyle.sf.net/config_sizes.html -->
        <module name="MethodLength"/>
        <module name="ParameterNumber">
	   <property name="max" value="11"/>
        </module>


        <!-- Checks for whitespace                               -->
        <!-- See http://checkstyle.sf.net/config_whitespace.html -->
        <module name="EmptyForIteratorPad"/>
        <module name="MethodParamPad"/>
        <module name="NoWhitespaceAfter"/>
            <!--property name="tokens" value="BNOT, DEC, DOT, INC, LNOT, UNARY_MINUS, UNARY_PLUS" />
        </module-->
        <module name="NoWhitespaceBefore"/>
        <module name="OperatorWrap"/>
        <module name="ParenPad"/>
        <module name="TypecastParenPad"/>
        <module name="WhitespaceAfter"/>
        <module name="WhitespaceAround">
            <property name="tokens" value="ASSIGN, BAND, BAND_ASSIGN, BOR,
                BOR_ASSIGN, BSR, BSR_ASSIGN, BXOR, BXOR_ASSIGN, COLON, DIV,
                DIV_ASSIGN, EQUAL, GE, GT, 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, LT, MINUS, MINUS_ASSIGN, MOD,
                MOD_ASSIGN, NOT_EQUAL, PLUS, PLUS_ASSIGN, QUESTION, SL,
                SLIST, SL_ASSIGN, SR, SR_ASSIGN, STAR, STAR_ASSIGN,
                TYPE_EXTENSION_AND" /> <!-- RCURLY removed -->
        </module>


        <!-- Modifier Checks                                    -->
        <!-- See http://checkstyle.sf.net/config_modifiers.html -->
        <module name="ModifierOrder"/>
        <!--module name="RedundantModifier"/-->


        <!-- Checks for blocks. You know, those {}'s         -->
        <!-- See http://checkstyle.sf.net/config_blocks.html -->
        <module name="AvoidNestedBlocks"/>
        <module name="EmptyBlock"/>
        <module name="LeftCurly"/>
        <module name="NeedBraces"/>
        <module name="RightCurly"/>


        <!-- Checks for common coding problems               -->
        <!-- See http://checkstyle.sf.net/config_coding.html -->
        <!-- module name="AvoidInlineConditionals"/-->
        <!--module name="DoubleCheckedLocking"/-->
        <module name="EmptyStatement"/>
        <module name="EqualsHashCode"/>
        <!-- Following "HiddenField" module is not compatible with builder inner class style. -->
        <!-- <module name="HiddenField"> -->
            <!-- <property name="ignoreConstructorParameter" value="true"/> -->
            <!-- <property name="ignoreSetter" value="true"/> -->
        <!-- </module> -->
        <module name="IllegalInstantiation"/>
        <module name="InnerAssignment"/>
        <!--
            Unable to use MagicNumber until maven plugin supports Checkstyle 5.3
            or, at least, until Checkstyle 5.3 is available in a maven repository
        <module name="MagicNumber">
            <property name="ignoreHashCodeMethod" value="true"/>
        </module-->
        <module name="MissingSwitchDefault"/>
        <module name="SimplifyBooleanExpression"/>
        <module name="SimplifyBooleanReturn"/>


        <!-- Checks for class design                         -->
        <!-- See http://checkstyle.sf.net/config_design.html -->
        <!--module name="DesignForExtension"/-->
        <module name="FinalClass"/>
        <module name="HideUtilityClassConstructor"/>
        <module name="InterfaceIsType"/>
        <module name="VisibilityModifier">
            <property name="protectedAllowed" value="true"/>
        </module>
        <module name="ThrowsCount">
            <property name="max" value="3"/>
        </module>



        <!-- Miscellaneous other checks.                   -->
        <!-- See http://checkstyle.sf.net/config_misc.html -->
        <module name="ArrayTypeStyle"/>
        <!-- module name="FinalParameters"/ -->
        <module name="TodoComment"/>
        <module name="UpperEll"/>

        <!-- Enable to suppress checkstyle errors by generic comment -->
        <!-- See https://checkstyle.sourceforge.io/config_filters.html#SuppressionCommentFilter -->
        <module name="SuppressionCommentFilter"/>
    </module>
</module>