checkstyle.xml

<?xml version="1.0"?>
<!--
  ~ Copyright (c) 2020-2021 VMware, Inc. or its affiliates, All Rights Reserved.
  ~
  ~ Licensed under the Apache License, Version 2.0 (the "License");
  ~ you may not use this file except in compliance with the License.
  ~ You may obtain a copy of the License at
  ~
  ~   https://www.apache.org/licenses/LICENSE-2.0
  ~
  ~ Unless required by applicable law or agreed to in writing, software
  ~ distributed under the License is distributed on an "AS IS" BASIS,
  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  ~ See the License for the specific language governing permissions and
  ~ limitations under the License.
  -->
<!DOCTYPE module PUBLIC
		"-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
		"https://checkstyle.org/dtds/configuration_1_3.dtd">

<!-- https://checkstyle.sourceforge.io/checks.html -->
<module name="Checker">
	<!-- Trailing Whitespace -->
	<module name="RegexpSingleline">
		<property name="format" value="\s+$"/>
		<property name="message" value="trailing whitespace"/>
	</module>

	<!-- AssertJ Requirement -->
	<module name="RegexpSingleline">
		<property name="format" value="org\.junit\.jupiter\.api\.Assertions\.assert"/>
		<property name="message" value="Please use AssertJ imports."/>
	</module>

	<module name="TreeWalker">
		<property name="fileExtensions" value="java"/>

		<module name="SuppressionCommentFilter"/>

		<!-- Annotations -->
		<module name="AnnotationLocation">
			<property name="allowSamelineSingleParameterlessAnnotation" value="false"/>
		</module>
		<module name="AnnotationUseStyle">
			<property name="elementStyle" value="compact"/>
		</module>
		<module name="MissingDeprecated"/>
		<module name="MissingOverride"/>
		<module name="PackageAnnotation"/>

		<!-- Block Checks -->
		<module name="AvoidNestedBlocks"/>
		<module name="EmptyBlock">
			<property name="option" value="text"/>
		</module>
		<module name="LeftCurly"/>
		<module name="NeedBraces"/>
		<module name="RightCurly">
			<property name="option" value="alone"/>
		</module>

		<!-- Class Design -->
		<module name="InterfaceIsType"/>
		<module name="FinalClass"/>
		<module name="MutableException"/>
		<module name="OneTopLevelClass"/>

		<!-- Coding -->
		<module name="CovariantEquals"/>
		<module name="DefaultComesLast"/>
		<module name="EmptyStatement"/>
		<module name="EqualsHashCode"/>
		<module name="ExplicitInitialization"/>
		<module name="MultipleVariableDeclarations"/>
		<module name="NestedForDepth">
			<property name="max" value="4"/>
		</module>
		<module name="NestedIfDepth">
			<property name="max" value="5"/>
		</module>
		<module name="NestedTryDepth">
			<property name="max" value="4"/>
		</module>
		<module name="OneStatementPerLine"/>
		<module name="PackageDeclaration"/>
		<module name="SimplifyBooleanExpression"/>
		<module name="SimplifyBooleanReturn"/>
		<module name="StringLiteralEquality"/>

		<!-- Imports -->
		<module name="AvoidStarImport"/>
		<module name="RedundantImport"/>
		<module name="UnusedImports"/>

		<!-- Miscellaneous -->
		<module name="ArrayTypeStyle"/>
		<module name="CommentsIndentation"/>
		<module name="OuterTypeFilename"/>
		<module name="UpperEll"/>

		<!-- Whitespaces -->
		<module name="GenericWhitespace"/>
		<module name="EmptyForInitializerPad"/>
		<module name="EmptyForIteratorPad"/>
		<module name="MethodParamPad"/>
		<module name="NoWhitespaceAfter"/>
		<module name="NoWhitespaceBefore"/>
		<module name="ParenPad"/>
		<module name="TypecastParenPad"/>
		<module name="WhitespaceAfter"/>
		<module name="WhitespaceAround">
			<property name="allowEmptyConstructors" value="true"/>
			<property name="allowEmptyTypes" value="true"/>
			<property name="allowEmptyLambdas" value="true"/>
		</module>
	</module>
</module>