src/checkstyle/checkstyle.xml

<?xml version="1.0"?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you 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

    http://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">
<module name="Checker">

	<module name="SuppressionFilter">
		<property name="file" value="${config_loc}/checkstyle-suppressions.xml"/>
	</module>

	<!-- Root Checks -->
	<module name="NewlineAtEndOfFile"/>

	<!-- TreeWalker Checks -->
	<module name="TreeWalker">

		<module name="SuppressionCommentFilter">
			<property name="offCommentFormat" value="CHECKSTYLE:OFF"/>
			<property name="onCommentFormat" value="CHECKSTYLE:ON"/>
		</module>

		<!-- Annotations -->
		<module name="AnnotationUseStyle">
			<property name="elementStyle" value="compact"/>
		</module>
		<module name="MissingOverride" />
		<module name="MissingDeprecated" />
		<module name="PackageAnnotation" />
		<module name="io.spring.javaformat.checkstyle.check.SpringAnnotationLocationCheck" />

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

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

		<!-- Coding -->
		<module name="CovariantEquals"/>
		<module name="EmptyStatement"/>
		<module name="EqualsHashCode"/>
		<module name="InnerAssignment"/>
		<module name="SimplifyBooleanExpression"/>
		<module name="SimplifyBooleanReturn"/>
		<module name="StringLiteralEquality"/>
		<module name="NestedForDepth">
			<property name="max" value="3"/>
		</module>
		<module name="NestedIfDepth">
			<property name="max" value="4"/>
		</module>
		<module name="NestedTryDepth">
			<property name="max" value="3"/>
		</module>
		<module name="MultipleVariableDeclarations"/>
		<module name="RequireThis">
			<property name="validateOnlyOverlapping" value="false"/>
			<property name="checkMethods" value="false"/>
		</module>
		<module name="OneStatementPerLine"/>

		<!-- Imports -->
		<module name="AvoidStarImport"/>
		<module name="AvoidStaticImport">
			<property name="excludes"
					  value="java.util.Objects.requireNonNull,
				org.assertj.core.api.Assertions.*,
				org.assertj.core.api.InstanceOfAssertFactories.type,
				org.awaitility.Awaitility.*,
				org.junit.jupiter.api.Assertions.*,
				org.junit.jupiter.params.provider.Arguments.*,
				org.junit.Assert.*,
				org.junit.Assume.*,
				org.junit.internal.matchers.ThrowableMessageMatcher.*,
				org.hamcrest.CoreMatchers.*,
				org.hamcrest.MatcherAssert.*,
				org.hamcrest.Matchers.*,
				org.mockito.Mockito.*,
				org.mockito.BDDMockito.*,
				org.mockito.ArgumentMatchers.*,
				org.springframework.kafka.test.hamcrest.KafkaMatchers.*,
				org.springframework.kafka.test.assertj.KafkaConditions.*"/>
		</module>
		<module name="IllegalImport"/>
		<module name="RedundantImport"/>
		<module name="UnusedImports">
			<property name="processJavadoc" value="true"/>
		</module>
		<module name="ImportOrder">
			<property name="groups" value="java,/^javax?\./,org,org.springframework,*"/>
			<property name="ordered" value="true"/>
			<property name="separated" value="true"/>
			<property name="option" value="top"/>
			<property name="sortStaticImportsAlphabetically" value="true"/>
		</module>

		<!-- Javadoc Comments -->
		<module name="JavadocType">
			<property name="scope" value="package"/>
		</module>
		<module name="JavadocMethod">
		</module>
		<module name="JavadocVariable">
			<property name="accessModifiers" value="public"/>
		</module>
		<module name="JavadocStyle">
			<property name="checkEmptyJavadoc" value="true"/>
		</module>
		<module name="NonEmptyAtclauseDescription"/>
		<module name="JavadocTagContinuationIndentation">
			<property name="offset" value="0"/>
		</module>
		<module name="AtclauseOrder">
			<property name="target" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF"/>
			<property name="tagOrder" value="@param, @since, @see, @version, @serial, @deprecated"/>
		</module>
		<module name="AtclauseOrder">
			<property name="target" value="METHOD_DEF, CTOR_DEF, VARIABLE_DEF"/>
			<property name="tagOrder" value="@param, @return, @throws, @since, @deprecated, @see"/>
		</module>

		<!-- Miscellaneous -->
		<module name="CommentsIndentation">
			<property name="tokens" value="BLOCK_COMMENT_BEGIN"/>
		</module>
		<module name="UpperEll"/>
		<module name="ArrayTypeStyle"/>
		<module name="OuterTypeFilename"/>

		<!-- Modifiers -->
		<module name="RedundantModifier"/>

		<!-- Regexp -->
		<module name="RegexpSinglelineJava">
			<property name="format" value="@+author\b"/>
			<property name="ignoreComments" value="false"/>
			<property name="message" value="Do not use author tags, the Git history records the authors"/>
		</module>
		<module name="RegexpSinglelineJava">
			<property name="format" value="^\t* +\t*\S"/>
			<property name="message"
					  value="Line has leading space characters; indentation should be performed with tabs only."/>
			<property name="ignoreComments" value="true"/>
		</module>
		<module name="RegexpSinglelineJava">
			<property name="maximum" value="0"/>
			<property name="format" value="org\.junit\.Assert\.assert"/>
			<property name="message"
					  value="Please use AssertJ imports."/>
			<property name="ignoreComments" value="true"/>
		</module>
		<module name="RegexpSinglelineJava">
			<property name="maximum" value="0"/>
			<property name="format" value="org\.junit\.jupiter\.api\.Assertions\.assert"/>
			<property name="message"
					  value="Please use AssertJ imports."/>
			<property name="ignoreComments" value="true"/>
		</module>
		<module name="com.puppycrawl.tools.checkstyle.checks.regexp.RegexpSinglelineJavaCheck">
			<property name="id" value="toLowerCaseWithoutLocale"/>
			<property name="format" value="\.toLowerCase\(\)"/>
			<property name="maximum" value="0"/>
			<property name="message"
					  value="String.toLowerCase() should be String.toLowerCase(Locale.ROOT)"/>
			<property name="ignoreComments" value="true"/>
		</module>
		<module name="com.puppycrawl.tools.checkstyle.checks.regexp.RegexpSinglelineJavaCheck">
			<property name="id" value="toUpperCaseWithoutLocale"/>
			<property name="format" value="\.toUpperCase\(\)"/>
			<property name="maximum" value="0"/>
			<property name="message"
					  value="String.toUpperCase() should be String.toUpperCase(Locale.ROOT)"/>
			<property name="ignoreComments" value="true"/>
		</module>
		<module name="Regexp">
			<property name="format" value="[ \t]+$"/>
			<property name="illegalPattern" value="true"/>
			<property name="message" value="Trailing whitespace"/>
		</module>
		<module name="Regexp">
			<property name="format" value="System.(out|err).print"/>
			<property name="illegalPattern" value="true"/>
			<property name="message" value="System.out or .err"/>
		</module>

		<!-- Whitespace -->
		<module name="GenericWhitespace"/>
		<module name="MethodParamPad"/>
		<module name="NoWhitespaceAfter">
			<property name="tokens" value="BNOT, DEC, DOT, INC, LNOT, UNARY_MINUS, UNARY_PLUS, ARRAY_DECLARATOR"/>
		</module>
		<module name="NoWhitespaceBefore"/>
		<module name="ParenPad"/>
		<module name="TypecastParenPad"/>
		<module name="WhitespaceAfter"/>
		<module name="WhitespaceAround"/>

	</module>
</module>