checkstyle.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
        "https://checkstyle.org/dtds/configuration_1_3.dtd">

<!--
    Palantir Baseline Checkstyle configuration.
    Authors: Robert Fink, Brian Worth, Merrick Zoubeiri, and many other contributors. Based in part on http://checkstyle.sourceforge.net/google_style.html
    Please keep checks alphabetized with one exception: "relaxed" checks are grouped together at the bottom for easier disabling.
    Check-specific comments reference documents internal to Palantir and can be safely ignored or removed.
 -->

<module name="Checker">
    <property name="charset" value="UTF-8"/>
    <property name="severity" value="error"/>

    <module name="FileTabCharacter"/> <!-- Java Style Guide: Whitespace characters -->
    <module name="NewlineAtEndOfFile"> <!-- Java Style Guide: Line ending: LF -->
        <property name="lineSeparator" value="lf"/>
    </module>
    <module name="RegexpHeader">
        <property name="header" value="^/\*$\n^ \* \(c\) Copyright \d{4} Palantir Technologies Inc\. All rights reserved\.$"/>
        <property name="fileExtensions" value=".java,.ts"/>
    </module>
    <module name="RegexpMultiline"> <!-- Development Practices: Writing good unit tests -->
        <property name="fileExtensions" value="java"/>
        <property name="format" value="@VisibleForTesting\s+(protected|public)"/>
        <property name="message" value="@VisibleForTesting members should be package-private."/>
    </module>
    <module name="RegexpSingleline"> <!-- No reference needed as this is evident. -->
        <property name="format" value="&lt;&lt;&lt;&lt;&lt;&lt;&lt;"/>
        <property name="message" value="Found (&lt;&lt;&lt;&lt;&lt;&lt;&lt;), so it looks like you had a merge conflict that compiles. Please fix it."/>
    </module>
    <module name="RegexpSingleline"> <!-- No reference needed as this is evident. -->
        <property name="format" value="&gt;&gt;&gt;&gt;&gt;&gt;&gt;"/>
        <property name="message" value="Found (&gt;&gt;&gt;&gt;&gt;&gt;&gt;), so it looks like you had a merge conflict that compiles. Please fix it."/>
    </module>
    <module name="RegexpSingleline">
        <property name="format" value="\s+$"/>
        <property name="message" value="Whitespace at end-of-line"/>
    </module>
    <module name="RegexpMultiline"> <!-- Java Style Guide: Vertical Whitespace -->
        <property name="fileExtensions" value="java"/>
        <property name="format" value="^\n\n$"/>
        <property name="message" value="Two consecutive blank lines are not permitted."/>
    </module>
    <module name="SuppressionFilter"> <!-- baseline-gradle: README.md -->
        <property name="file" value="${config_loc}/checkstyle-suppressions.xml"/>
    </module>
    <module name="SuppressionFilter"> <!-- baseline-gradle: README.md -->
        <!-- custom-suppressions.xml allows users to specify suppresions that will not be overriden by baselineUpdateConfig -->
        <property name="file" value="${config_loc}/custom-suppressions.xml"/>
        <property name="optional" value="true"/>
    </module>
    <module name="SuppressWarningsFilter"/> <!-- baseline-gradle: README.md -->
    <module name="BeforeExecutionExclusionFileFilter">
        <property name="fileNamePattern" value="module\-info\.java$"/>
    </module>
    <module name="TreeWalker">
        <module name="SuppressionCommentFilter"/> <!-- baseline-gradle: README.md -->
        <module name="SuppressionCommentFilter">
            <property name="offCommentFormat" value="CHECKSTYLE.OFF\: ([\w\|]+)"/>
            <property name="onCommentFormat" value="CHECKSTYLE.ON\: ([\w\|]+)"/>
            <property name="checkFormat" value="$1"/>
        </module>
        <module name="AbbreviationAsWordInName"> <!-- Java Style Guide: Camel case : defined -->
            <property name="ignoreFinal" value="false"/>
            <property name="allowedAbbreviationLength" value="1"/>
        </module>
        <module name="AnnotationLocation"> <!-- Java Style Guide: Annotations -->
            <property name="tokens" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF"/>
        </module>
        <module name="AnnotationLocation"> <!-- Java Style Guide: Annotations -->
            <property name="tokens" value="VARIABLE_DEF"/>
            <property name="allowSamelineMultipleAnnotations" value="true"/>
        </module>
        <module name="AnnotationUseStyle"/> <!-- Java Style Guide: Annotations -->
        <module name="ArrayTypeStyle"/> <!-- Java Style Guide: No C-style array declarations -->
        <module name="AvoidEscapedUnicodeCharacters"> <!-- Java Style Guide: Non-ASCII characters -->
            <property name="allowEscapesForControlCharacters" value="true"/>
            <property name="allowByTailComment" value="true"/>
            <property name="allowNonPrintableEscapes" value="true"/>
        </module>
        <module name="AvoidNestedBlocks"> <!-- Java Coding Guidelines: Avoid nested blocks -->
            <property name="allowInSwitchCase" value="true"/>
        </module>
        <module name="AvoidStarImport"/> <!-- Java Style Guide: No wildcard imports -->
        <module name="AvoidStaticImport"> <!-- Java Style Guide: No static imports -->
            <property name="excludes" value="
                com.google.common.base.Preconditions.*,
                com.palantir.logsafe.Preconditions.*,
                java.util.Collections.*,
                java.util.stream.Collectors.*,
                org.apache.commons.lang3.Validate.*,
                org.assertj.core.api.Assertions.*,
                org.mockito.Mockito.*"/>
        </module>
        <module name="ClassTypeParameterName"> <!-- Java Style Guide: Type variable names -->
            <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
            <message key="name.invalidPattern" value="Class type name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="CovariantEquals"/> <!-- Java Coding Guidelines: Override ``Object#equals`` consistently -->
        <module name="DefaultComesLast"/> <!-- Java Style Guide: The default case is present -->
        <module name="EmptyBlock"> <!-- Java Style Guide: Empty blocks: documented -->
            <property name="option" value="TEXT"/>
        </module>
        <module name="EmptyCatchBlock"> <!-- Java Style Guide: Empty blocks: documented -->
            <property name="exceptionVariableName" value="expected"/>
        </module>
        <module name="EmptyForInitializerPad"/> <!-- Java Style Guide: Horizontal whitespace -->
        <module name="EmptyLineSeparator"> <!-- Java Style Guide: Source file structure -->
            <property name="tokens" value="IMPORT, CLASS_DEF, ENUM_DEF, INTERFACE_DEF, CTOR_DEF, STATIC_INIT, INSTANCE_INIT, VARIABLE_DEF"/>
            <property name="allowNoEmptyLineBetweenFields" value="true"/>
        </module>
        <module name="EmptyStatement"/> <!-- Java Style Guide: One statement per line -->
        <module name="EqualsHashCode"/>
        <module name="FallThrough"/> <!-- Java Style Guide: Fall-through: commented -->
        <module name="GenericWhitespace"> <!-- Java Style Guide: Horizontal whitespace -->
            <message key="ws.followed" value="GenericWhitespace ''{0}'' is followed by whitespace."/>
            <message key="ws.preceded" value="GenericWhitespace ''{0}'' is preceded with whitespace."/>
            <message key="ws.illegalFollow" value="GenericWhitespace ''{0}'' should followed by whitespace."/>
            <message key="ws.notPreceded" value="GenericWhitespace ''{0}'' is not preceded with whitespace."/>
        </module>
        <module name="HiddenField"> <!-- Java Coding Guide: Avoid shadowing -->
            <property name="ignoreConstructorParameter" value="true"/>
            <property name="ignoreSetter" value="true"/>
            <property name="setterCanReturnItsClass" value="true"/>
        </module>
        <module name="HideUtilityClassConstructor"/> <!-- Java Coding Guidelines: Private constructors -->
        <module name="IllegalImport"> <!-- Java Coding Guidelines: Use JUnit 4-style test classes and assertions -->
            <property name="illegalPkgs" value="junit.framework"/>
            <message key="import.illegal" value="Use JUnit 4-style (org.junit.*) test classes and assertions instead of JUnit 3 (junit.framework.*)."/>
        </module>
        <module name="IllegalImport"> <!-- Only relevant for pre-Java 11 because javafx is gone completely in Java 11 -->
            <property name="id" value="BanJavafx"/>
            <property name="illegalPkgs" value="javafx"/>
            <message key="import.illegal" value="Must not import javafx classes because some OpenJDK builds do not include javafx."/>
        </module>
        <module name="IllegalImport"> <!-- Java Coding Guidelines: Import the canonical package -->
            <property name="illegalPkgs" value="org.elasticsearch.common.base, com.clearspring.analytics.util, org.spark_project.guava"/>
            <message key="import.illegal" value="Must not import repackaged classes."/>
        </module>
        <module name="IllegalImport"> <!-- Java Coding Guidelines: Import the canonical package -->
            <property name="id" value="BanShadedClasses"/>
            <property name="illegalPkgs" value=".*\.(repackaged|shaded|thirdparty)"/>
            <property name="regexp" value="true" />
            <message key="import.illegal" value="Must not import repackaged classes."/>
        </module>
        <module name="IllegalImport">
            <property name="illegalPkgs" value="^org\.gradle\.(internal|.*\.internal)"/>
            <property name="regexp" value="true" />
            <message key="import.illegal" value="Do not rely on gradle internal classes as these may change in minor releases - use org.gradle.api versions instead."/>
        </module>
        <module name="IllegalImport">
            <property name="illegalPkgs" value="sun"/>
            <message key="import.illegal" value="Must not use Oracle's Java implementation details. See http://www.oracle.com/technetwork/java/faq-sun-packages-142232.html ."/>
        </module>
        <module name="IllegalImport">
            <property name="illegalPkgs" value="org.apache.commons.lang"/>
            <message key="import.illegal" value="lang is deprecated, use lang3 instead."/>
        </module>
        <module name="IllegalImport">
            <property name="illegalPkgs" value="org.apache.commons.math"/>
            <message key="import.illegal" value="math is deprecated, use math3 instead."/>
        </module>
        <module name="IllegalImport">
            <property name="id" value="BanLoggingImplementations"/>
            <property name="illegalPkgs" value="org.apache.log4j, org.apache.logging.log4j, java.util.logging, ch.qos.logback"/>
            <message key="import.illegal" value="Use SLF4J instead of a logging framework directly."/>
        </module>
        <module name="IllegalImport">
            <property name="illegalClasses" value="com.google.common.base.Optional, com.google.common.base.Supplier"/>
            <message key="import.illegal" value="Use the Java8 version of Guava objects."/>
        </module>
        <module name="IllegalInstantiation"> <!-- Java Coding Guidelines: Never instantiate primitive types -->
            <property name="classes" value="java.lang.Boolean"/>
            <property name="classes" value="java.lang.Byte"/>
            <property name="classes" value="java.lang.Character"/>
            <property name="classes" value="java.lang.Double"/>
            <property name="classes" value="java.lang.Float"/>
            <property name="classes" value="java.lang.Integer"/>
            <property name="classes" value="java.lang.Long"/>
        </module>
        <module name="IllegalThrows"/> <!-- Java Coding Guidelines: Throwable, Error, RuntimeException: Not declared -->
        <module name="IllegalTokenText"> <!-- Java Style Guide: Special escape sequences -->
            <property name="tokens" value="STRING_LITERAL, CHAR_LITERAL"/>
            <property name="format" value="\\u00(08|09|0(a|A)|0(c|C)|0(d|D)|22|27|5(C|c))|\\(0(10|11|12|14|15|42|47)|134)"/>
            <property name="message" value="Avoid using corresponding octal or Unicode escape."/>
        </module>
        <module name="IllegalType"> <!-- Java Coding Guide: Limit coupling on concrete classes -->
            <property name="illegalClassNames" value="java.util.ArrayList, java.util.HashSet, java.util.HashMap, java.util.LinkedList, java.util.LinkedHashMap, java.util.LinkedHashSet, java.util.TreeSet, java.util.TreeMap, com.google.common.collect.ArrayListMultimap, com.google.common.collect.ForwardingListMultimap, com.google.common.collect.ForwardingMultimap, com.google.common.collect.ForwardingSetMultimap, com.google.common.collect.ForwardingSortedSetMultimap, com.google.common.collect.HashMultimap, com.google.common.collect.LinkedHashMultimap, com.google.common.collect.LinkedListMultimap, com.google.common.collect.TreeMultimap"/>
        </module>
        <module name="IllegalType">
            <property name="id" value="BanGuavaCaches"/>
            <property name="illegalClassNames" value="com.google.common.cache.CacheBuilder, com.google.common.cache.Cache, com.google.common.cache.LoadingCache"/>
            <message key="illegal.type" value="Do not use Guava caches, they are outperformed by and harder to use than Caffeine caches"/>
        </module>
        <module name="ImportOrder"> <!-- Java Style Guide: Ordering and spacing -->
            <property name="groups" value="/.*/"/>
            <property name="option" value="top"/>
            <property name="separated" value="true"/>
            <property name="sortStaticImportsAlphabetically" value="true"/>
        </module>
        <module name="InnerAssignment"/> <!-- Java Coding Guidelines: Inner assignments: Not used -->
        <module name="LeftCurly"/> <!-- Java Style Guide: Nonempty blocks: K & R style -->
        <module name="LineLength"> <!-- Java Style Guide: No line-wrapping -->
            <property name="max" value="120"/>
            <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
        </module>
        <module name="MemberName"> <!-- Java Style Guide: Non-constant field names -->
            <property name="format" value="^[a-z][a-zA-Z0-9]+$"/>
            <message key="name.invalidPattern" value="Member name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="MethodName"> <!-- Java Style Guide: Method names -->
            <property name="format" value="^[a-z][a-zA-Z0-9_]+$"/>
            <message key="name.invalidPattern" value="Method name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="MethodParamPad"/> <!-- Java Style Guide: Horizontal whitespace -->
        <module name="MissingDeprecated"/> <!-- Java Coding Guide: Deprecate per annotation and Javadoc -->
        <module name="ModifiedControlVariable"/> <!-- Java Coding Guide: For-loop control variables: never modified -->
        <module name="ModifierOrder"/> <!-- Java Style Guide: Modifiers -->
        <module name="MultipleVariableDeclarations"/> <!-- Java Style Guide: One variable per declaration -->
        <module name="MutableException"/> <!-- Java Coding Guidelines: Exceptions: Always immutable -->
        <module name="NeedBraces"/> <!-- Java Style Guide: Braces are used where optional -->
        <module name="NoClone"/> <!-- Java Coding Guidelines: Never override Object#finalize or Object#clone -->
        <module name="NoFinalizer"/> <!-- Java Coding Guidelines: Never override Object#finalize -->
        <module name="NoLineWrap"/> <!-- Java Style Guide: No line-wrapping -->
        <module name="NoWhitespaceAfter"> <!-- Java Style Guide: Horizontal whitespace -->
            <property name="allowLineBreaks" value="false"/>
            <property name="tokens" value="BNOT,DEC,DOT,INC,LNOT,UNARY_MINUS,UNARY_PLUS"/>
        </module>
        <module name="NoWhitespaceBefore"> <!-- Java Style Guide: Horizontal whitespace -->
            <property name="allowLineBreaks" value="true"/>
        </module>
        <module name="OneStatementPerLine"/> <!-- Java Style Guide: One statement per line -->
        <module name="OneTopLevelClass"/> <!-- Java Style Guide: Exactly one top-level class declaration -->
        <module name="OperatorWrap"> <!-- Java Style Guide: Where to break -->
            <property name="option" value="NL"/>
            <property name="tokens" value="BAND, BOR, BSR, BXOR, DIV, EQUAL, GE, GT, LAND, LE, LITERAL_INSTANCEOF, LOR, LT, MINUS, MOD, NOT_EQUAL, PLUS, QUESTION, SL, SR, STAR "/>
        </module>
        <module name="OuterTypeFilename"/> <!-- Java Style Guide: File name -->
        <module name="OverloadMethodsDeclarationOrder"/> <!-- Java Style Guide: Overloads: never split -->
        <module name="PackageAnnotation"/> <!-- Java Style Guide: Package statement -->
        <module name="PackageDeclaration"/> <!-- Java Style Guide: Package statement -->
        <module name="PackageName"> <!-- Java Style Guide: Package names -->
            <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
            <message key="name.invalidPattern" value="Package name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="ParameterAssignment"/> <!-- Java Coding Guidelines: Final variables and parameters -->
        <module name="ParenPad"/> <!-- Java Style Guide: Horizontal whitespace -->
        <module name="RedundantImport"/> <!-- Java Style Guide: No unused imports -->
        <module name="RedundantModifier"/> <!-- Java Coding Guidelines: Avoid redundant modifiers -->
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Use appropriate assertion methods -->
            <property name="format" value="assertEquals\(false,"/>
            <property name="message" value="Use assertFalse() instead."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Use appropriate assertion methods -->
            <property name="format" value="assertEquals\(null,"/>
            <property name="message" value="Use assertNull() instead."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Use appropriate assertion methods -->
            <property name="format" value="assertEquals\(true,"/>
            <property name="message" value="Use assertTrue() instead."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Use appropriate assertion methods -->
            <property name="format" value="assertFalse\(.*[!=]="/>
            <property name="message" value="Use better assertion method(s): assertEquals(), assertNull(), assertSame(), etc."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Use appropriate assertion methods -->
            <property name="format" value="assertTrue\(!"/>
            <property name="message" value="Use assertFalse()."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Use appropriate assertion methods -->
            <property name="format" value="assertTrue\(.*[!=]="/>
            <property name="message" value="Use better assertion method(s): assertEquals(), assertNull(), assertSame(), etc."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Avoid Generics clutter where possible -->
            <property name="format" value="Collections\.EMPTY_LIST"/>
            <property name="message" value="Use Collections.emptyList() or, better, ImmutableList.of()."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Avoid Generics clutter where possible -->
            <property name="format" value="Collections\.EMPTY_MAP"/>
            <property name="message" value="Use Collections.emptyMap() or, better, ImmutableMap.of()."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Avoid Generics clutter where possible -->
            <property name="format" value="Collections\.EMPTY_SET"/>
            <property name="message" value="Use Collections.emptySet() or, better, ImmutableSet.of()."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Use appropriate assertion methods -->
            <property name="format" value="CoreMatchers\.equalTo"/>
            <property name="message" value="Use Assert.assertEquals()."/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="id" value="BanJacksonFindAndRegisterModulesMethod"/>
            <property name="format" value="findAndRegisterModules"/>
            <property name="message" value="Use ObjectMapper#registerModule(&lt;yourModule&gt;) explicitly. ObjectMapper#findAndRegisterModules() is dangerous because it will change behaviour depending on which modules are on your classpath (including transitive dependencies)."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Use appropriate assertion methods -->
            <property name="format" value="CoreMatchers\.notNull"/>
            <property name="message" value="Use better assertion method(s): Assert.assertEquals(), assertNull(), assertSame(), etc."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Avoid Generics clutter where possible -->
            <property name="format" value="ImmutableList\.Builder.*new ImmutableList\.Builder"/>
            <property name="message" value="Use ImmutableList.builder() for variable assignment."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Avoid Generics clutter where possible -->
            <property name="format" value="ImmutableMap\.Builder.*new ImmutableMap\.Builder"/>
            <property name="message" value="Use ImmutableMap.builder() for variable assignment."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Avoid Generics clutter where possible -->
            <property name="format" value="ImmutableSet\.Builder.*new ImmutableSet\.Builder"/>
            <property name="message" value="Use ImmutableSet.builder() for variable assignment."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Check parameters for validity -->
            <property name="format" value="Preconditions\.checkNotNull\((?!.*,)([^()]*(\(([^()]*|\(([^()]*|\([^()]*\))*\))*\)[^()]*)*)\)"/>
            <property name="message" value="Use Preconditions.checkNotNull(Object, String)."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Check parameters for validity -->
            <property name="format" value="Validate\.notNull\((?!.*,)([^()]*(\(([^()]*|\(([^()]*|\([^()]*\))*\))*\)[^()]*)*)\)"/>
            <property name="message" value="Use Validate.notNull(Object, String)."/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="format" value="^\s*super\(\);"/>
            <property name="message" value="This is unnecessary; please delete."/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="format" value="@return.*\.$"/>
            <property name="message" value="Please delete the period."/>
        </module>
        <module name="RegexpSinglelineJava"> <!-- Java Style Guide: Horizontal whitespace -->
            <property name="format" value="\s+$"/>
            <property name="message" value="Trailing whitespace is not allowed."/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="format" value="\? extends Object\W"/>
            <property name="message" value="Use ? rather than ? extends Object."/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="format" value="(?i)log(ger)?\.(debug|info|warn|error)\(.*%[sd]"/>
            <property name="message" value="SLF4J loggers support '{}' style formatting."/>
            <property name="ignoreComments" value="true"/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="format" value="\.printStackTrace\(\)"/>
            <property name="message" value="printStackTrace is not generally allowed."/>
            <property name="ignoreComments" value="true"/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="id" value="BanSystemOut"/>
            <property name="format" value="System\.out\."/>
            <property name="message" value="Logging with System.out is not allowed because it has no metadata and can't be configured at runtime. Please use an SLF4J logger instead, e.g. log.info(&quot;Message&quot;)."/>
            <property name="ignoreComments" value="true"/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="id" value="BanSystemErr"/>
            <property name="format" value="System\.err\."/>
            <property name="message" value="Logging with System.err is not allowed because it has no metadata and can't be configured at runtime. Please use an SLF4J logger instead, e.g. log.info(&quot;Message&quot;)."/>
            <property name="ignoreComments" value="true"/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="format" value="\bCharsets\."/>
            <property name="message" value="Use JDK StandardCharsets instead of alternatives."/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="format" value="\bCharset.defaultCharset\("/>
            <property name="message" value="Use explicit charset (e.g. StandardCharsets.UTF-8) instead of default."/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="format" value="\bIOUtils\.toString\("/>
            <property name="message" value="Prefer Guava''s [CharStreams,Files,Resources].toString to avoid charset/stream closing issues."/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="format" value="\/\/TODO|\/\/ TODO(?!\([^()\s]+\): )"/>
            <property name="message" value="TODO format: // TODO(#issue): explanation"/>
        </module>
        <module name="RegexpSinglelineJava">
            <property name="format" value="(void setUp\(\))|(void setup\(\))|(void setupStatic\(\))|(void setUpStatic\(\))|(void beforeTest\(\))|(void teardown\(\))|(void tearDown\(\))|(void beforeStatic\(\))|(void afterStatic\(\))"/>
            <property name="message" value="Test setup/teardown methods are called before(), beforeClass(), after(), afterClass(), but not setUp, teardown, etc."/>
        </module>
        <module name="RightCurly"> <!-- Java Style Guide: Nonempty blocks: K & R style -->
            <property name="option" value="same"/>
            <property name="tokens" value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_DO"/>
        </module>
        <module name="RightCurly"> <!-- Java Style Guide: Nonempty blocks: K & R style -->
            <property name="option" value="alone"/>
            <property name="tokens" value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, STATIC_INIT, INSTANCE_INIT"/>
        </module>
        <module name="SeparatorWrap"> <!-- Java Style Guide: Where to break -->
            <property name="tokens" value="DOT"/>
            <property name="option" value="nl"/>
        </module>
        <module name="SeparatorWrap"> <!-- Java Style Guide: Where to break -->
            <property name="tokens" value="COMMA"/>
            <property name="option" value="EOL"/>
        </module>
        <module name="SimplifyBooleanExpression"/> <!-- Java Coding Guidelines: Keep Boolean expressions simple -->
        <module name="SimplifyBooleanReturn"/> <!-- Java Coding Guidelines: Keep Boolean expressions simple -->
        <module name="StaticVariableName"/> <!-- Java Style Guide: Naming -->
        <module name="StringLiteralEquality"/> <!-- Java Coding Guidelines: String equality: use String#equals -->
        <module name="SuperClone"/>
        <module name="SuppressWarnings">
            <property name="format" value="serial"/>
        </module>
        <module name="SuppressWarningsHolder" />  <!-- Required for SuppressWarningsFilter -->
        <module name="TypeName"> <!-- Java Style Guide: Class names -->
            <message key="name.invalidPattern" value="Type name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="TypecastParenPad"/> <!-- Java Style Guide: Horizontal whitespace -->
        <module name="UnnecessaryParentheses"/>
        <module name="UnusedImports"> <!-- Java Style Guide: No unused imports -->
            <property name="processJavadoc" value="true"/>
        </module>
        <module name="UpperEll"/> <!-- Java Style Guide: Numeric Literals -->
        <module name="VisibilityModifier"/> <!-- Java Coding Guidelines: Minimize mutability -->
        <module name="WhitespaceAfter"/> <!-- Java Style Guide: Horizontal whitespace -->
        <module name="WhitespaceAround"> <!-- Java Style Guide: Horizontal whitespace -->
            <property name="allowEmptyConstructors" value="true"/>
            <property name="allowEmptyMethods" value="true"/>
            <property name="allowEmptyTypes" value="true"/>
            <property name="allowEmptyLoops" value="true"/>
            <property name="allowEmptyLambdas" value="true"/>
            <property name="ignoreEnhancedForColon" value="false"/>
            <message key="ws.notFollowed" value="WhitespaceAround: ''{0}'' is not followed by whitespace. Empty blocks may only be represented as '{}' when not part of a multi-block statement (4.1.3)"/>
            <message key="ws.notPreceded" value="WhitespaceAround: ''{0}'' is not preceded with whitespace."/>
        </module>

        <!-- Stricter checks begin: delete some or all of the following for faster prototyping, but please restore before pushing to production. -->

        <module name="AtclauseOrder"> <!-- Java Style Guide: At-clauses -->
            <property name="tagOrder" value="@param, @return, @throws, @deprecated"/>
            <property name="target" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF, VARIABLE_DEF"/>
        </module>
        <module name="CyclomaticComplexity"/> <!-- Java Coding Guidelines: Reduce Cyclomatic Complexity -->
        <module name="DesignForExtension"> <!-- Java Coding Guidelines: Design for extension -->
            <property name="ignoredAnnotations" value="ParameterizedTest, Test, Before, BeforeEach, After, AfterEach, BeforeClass, BeforeAll, AfterClass, AfterAll"/>
        </module>
        <module name="JavadocMethod"> <!-- Java Style Guide: Where Javadoc is used -->
            <property name="scope" value="public"/>
            <property name="allowMissingParamTags" value="true"/>
            <property name="allowMissingThrowsTags" value="true"/>
            <property name="allowMissingReturnTag" value="true"/>
            <property name="minLineCount" value="99999999"/>
            <property name="allowedAnnotations" value="Override, Test"/>
            <property name="allowThrowsTagsForSubclasses" value="true"/>
        </module>
        <module name="JavadocStyle"/> <!-- Java Style Guide: Javadoc -->
        <module name="JavadocTagContinuationIndentation"> <!-- Java Style Guide: At-clauses -->
            <property name="offset" value="0"/>
        </module>
        <module name="LocalFinalVariableName"/> <!-- Java Style Guide: Local variable names -->
        <module name="LocalVariableName"> <!-- Java Style Guide: Local variable names -->
            <property name="tokens" value="VARIABLE_DEF"/>
            <property name="format" value="^[a-z][a-zA-Z0-9]+$"/>
            <property name="allowOneCharVarInForLoop" value="true"/>
            <message key="name.invalidPattern" value="Local variable name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="MethodLength"/> <!-- Java Coding Guide: Methods and functions: focused, crisp, concise -->
        <module name="MethodTypeParameterName"> <!-- Java Style Guide: Type variable names -->
            <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
            <message key="name.invalidPattern" value="Method type name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="NestedForDepth">
            <property name="max" value="2"/>
        </module>
        <module name="NestedTryDepth"/> <!-- Java Coding Guide: Try/catch blocks: never nested -->
        <module name="NonEmptyAtclauseDescription"/> <!-- Java Style Guide: At-clauses -->
        <module name="ParameterName"> <!-- Java Style Guide: Parameter names -->
            <property name="format" value="^_?[a-z][a-zA-Z0-9]+$"/>
            <message key="name.invalidPattern" value="Parameter name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="SummaryJavadocCheck"> <!-- Java Coding Guidelines: Javadoc -->
            <property name="forbiddenSummaryFragments" value="^@return the *|^This method returns |^A [{]@code [a-zA-Z0-9]+[}]( is a )"/>
        </module>

        <!-- Stricter checks end -->
    </module>
</module>